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Glossory of Physics
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="blue"]Absorption[/COLOR][/SIZE][/FONT][/B] It happens when wave passes through a medium and gives up some of its energy. [FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"][B]Acceleration[/COLOR][/SIZE][/FONT][/B] Acceleration is the rate of increase of velocity. Acceleration tells you how much faster or slower a moving object gets every second. A negative acceleration is called a deceleration. The SI Unit of acceleration is the metre per second per second (ms-2) [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Acceleration due to Gravity[/COLOR][/SIZE][/FONT][/B] This is the acceleration caused by the gravitational pull of a planet. On Earth, the strength of the acceleration due to gravity is roughly 10 ms-2. The acceleration due to gravity is often given the symbol 'g'. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Accommodation[/COLOR][/SIZE][/FONT][/B] Accommodation relates to the ability of the eye to change its focal length and so focus on objects at a range of distances. To focus on a close object, the eye lens will be fat (having a short focal length). To focus on a far object, the lens will be pulled into a thin shape having a long focal length. Failure of accommodation gives rise to long-sightedness and short-sightedness. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Activity[/COLOR][/SIZE][/FONT][/B] The activity of a sample of radioactive material is the number of disintegrations per second taking place in that particular sample. The SI unit of activity is the becquerel (Bq). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Aerodynamic[/COLOR][/SIZE][/FONT][/B] Aerodynamic objects have minimal air resistance. This means that they can move at greater speed through the air. Remember that as objects go faster the aerodynamic drag increases. Therefore, an aerodynamic object will be able to travel faster than a non-aerodynamic one! [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Alpha (a) Radiation[/COLOR][/SIZE][/FONT][/B] a (alpha) radiation consists of slow moving helium nuclei. These nuclei are released during the disintegration of an unstable nucleus. a radiation will be stopped by a few centimetres of air, or a sheet of paper. It is a strongly ionising radiation, due in part to its relatively large mass - it is about 8000 times as massive as the electrons in b radiation! The helium nuclei are positively charged. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Alternating Current (a.c.)[/COLOR][/SIZE][/FONT][/B] Electrical current continually changes direction in an a.c. power supply (as opposed to direct current (d.c.)) [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Alternator[/COLOR][/SIZE][/FONT][/B] This is a device for generating a.c. electricity. It consists of rotor coils (with a d.c. supply) and stator coils which produce the a.c. electricity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ampere[/COLOR][/SIZE][/FONT][/B] The ampere is the SI unit of electrical current. At a simple level it can be defined as the number of coulombs of electrical charge flowing per second. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Amplifier[/COLOR][/SIZE][/FONT][/B] An amplifier is a component of an electronic system, such as a radio or TV which makes all the input signals louder. Ideally, an amplifier will increase the amplitude of all input signals by the same factor. Amplifiers require a power supply which can be battery or mains. The voltage gain or the power gain can be used to describe how much amplification is taking place. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Amplitude [/COLOR][/SIZE][/FONT][/B] This is the height of a wave, measured vertically from the centre line to a crest or a trough. The SI unit is the metre, although in some contexts amplitudes may be given in volts. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Amplitude Modulation [/COLOR][/SIZE][/FONT][/B] Amplitude modulation refers to the changing of the amplitude of a radio-frequency or microwave frequency carrier wave. The other method of modulation is called frequency modulation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Analogue[/COLOR][/SIZE][/FONT][/B] Analogue signals should be compared with digital signals. Analogue signals are continuous. As an example, a microphone is an analogue input device. This is because it can produce a range of voltage levels. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]AND Gate[/COLOR][/SIZE][/FONT][/B] An AND gate is a logical device. It usually takes two inputs (although more are possible) and produces only one output. The logic state of the output depends on the logic state of the inputs. [FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"][B]Angle of Incidence [/COLOR][/SIZE][/FONT][/B] The angle between the normal line and a ray or wave incident to a surface. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Angular magnification[/COLOR][/SIZE][/FONT][/B] The factor by which an image's apparent angular size is increased (or decreased). Cf. magnification. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Angular momentum [/COLOR][/SIZE][/FONT][/B] A measure of rotational motion; a conserved quantity for a closed system. [FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"][B]Angle of Reflection [/COLOR][/SIZE][/FONT][/B] The angle between the normal line and a ray or wave reflected from a surface. [FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"][B]Asteroid[/COLOR][/SIZE][/FONT][/B] An asteriod is a lump of rock which orbits around the sun. (The biggest asteroids are about 100km across, although many are 1km or less across. Asteroids orbit the Sun in the asteroid belt, between the orbits of Mars and Jupiter.) [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Atom[/COLOR][/SIZE][/FONT][/B] The basic unit of one of the chemical elements. [FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"][B]Average Speed[/COLOR][/SIZE][/FONT][/B] The average speed of an object is defined as the distance traveled divided by the time elapsed. Remember that average speed is different from instantaneous speed. [FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"][B]Audio Wave[/COLOR][/SIZE][/FONT][/B] A sound wave, but usually in the context of modulation and radio transmission [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Axis[/COLOR][/SIZE][/FONT][/B] An arbitrarily chosen point used in the definition of angular momentum. Any object whose direction changes relative to the axis is considered to have angular momentum. No matter what axis is chosen, the angular momentum of a closed system is conserved. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Background Radiation[/COLOR][/SIZE][/FONT][/B] Background radiation is the radiation which occurs naturally in the rocks, air and water around us. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Battery[/COLOR][/SIZE][/FONT][/B] A battery is a number (or battery) of cells, connected in series with the positive terminal of one cell connected to the negative of the next. Batteries provide a d.c.(direct current) source of electrical energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Beam[/COLOR][/SIZE][/FONT][/B] The particle stream produced by an accelerator usually clustered in bunches. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]b (beta) radiation[/COLOR][/SIZE][/FONT][/B] b (beta) radiation consists of fast moving electrons. These electrons are produced as a result of transitions that take place in unstable nuclei. b radiation can be stopped by a few millimetres of aluminium. It is an ionising radiation, not as strongly ionising as a (alpha) radiation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Big-bang Theory[/COLOR][/SIZE][/FONT][/B] The 'big-bang theory' of cosmology tries to explain the origin of the universe as an explosive event, where space, time and matter came into being. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Black Hole[/COLOR][/SIZE][/FONT][/B] A collapsed star from which no light can escape, due to the intense gravitational field. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Block Diagram[/COLOR][/SIZE][/FONT][/B] In electronics, a block diagram provides a simple way of analysing how a system works. Block diagrams don't show details of how components work, but simply show how information or signals should travel through the system. They are usually drawn using rectangles and arrows. |
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[/COLOR][/SIZE][/FONT][/CENTER][/B] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Capacitor [/COLOR][/SIZE][/FONT][/B] A capacitor is a device which can store electrical charge. Capacitors are often used to introduce a time delay in electronic circuits. The SI unit of capacitance is the farad. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Carrier Wave[/COLOR][/SIZE][/FONT][/B] Carrier waves are used to carry information from transmitter to receiver. Thecarrier wave will be radio or microwave frequency. There are two methods of using the carrier wave to carry information - amplitude modulation and frequency modulation. In radio transmissions for example, the carrier is of a much higher frequency than the audio wave which is to be transmitted. The higher the frequency of the carrier, the higher the quality of the transmitted signal. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Cathode rays [/COLOR][/SIZE][/FONT][/B] Negatively charged particles (electrons) that are emitted from a negative terminal in an evacuated glass tube. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Cell [/COLOR][/SIZE][/FONT][/B] In electricity, a cell is a source of d.c. electricity. A cell can be made using two different metals inserted into a salt solution, for example. The metals react with the salt solution at different rates and in so doing, generate a small electrical current. Many cells can be combined to produce a battery of cells. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Celsius scale of temperature[/COLOR][/SIZE][/FONT][/B] In the celsius scale of temperature, the ice-point is taken as taken as the lower fixed point (0 deg C ) and the steam-point is taken as the upper fixed point (100 deg C). The interval between the ice point and steam point is divided into 100 equal divisions. Thus, the unit division on this scale is 1degC. This scale was earlier called the centigrade scale. 1 deg C = 9/5 deg F. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Center of mass[/COLOR][/SIZE][/FONT][/B] The balance point of an object. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Centigrade [/COLOR][/SIZE][/FONT][/B] Alternate name for the Celsius scale. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Centrifugal force [/COLOR][/SIZE][/FONT][/B] An apparent outward force on an object following a circular path that. This force is a consequence of the third law of motion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Centripetal force [/COLOR][/SIZE][/FONT][/B] The force required to pull an object out of its natural straight-line path and into a circular path. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Chain reaction[/COLOR][/SIZE][/FONT][/B] A self-sustaining reaction where some of the products are able to produce more reactions of the same kind; in a nuclear chain reaction neutrons are the products that produce more nuclear reactions in a self-sustaining series [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Charge[/COLOR][/SIZE][/FONT][/B] A numerical rating of how strongly an object participates in electrical forces. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Chemical Potential Energy[/COLOR][/SIZE][/FONT][/B] Chemical energy is a form of potential energy because it is stored energy. Energy stored in food, torch batteries and explosives like dynamite is all chemical energy. Chemical energy is released in a chemical reaction (like combustion of explosives or respiration in plant and animal cells). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Circuit[/COLOR][/SIZE][/FONT][/B] An electrical device in which charge can come back to its starting point and be recycled rather than getting stuck in a dead end. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Circular Motion[/COLOR][/SIZE][/FONT][/B] The motion of a body along a circular path is called circular motion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Clock Pulse Generator[/COLOR][/SIZE][/FONT][/B] A simple circuit using a capacitor, resistor and transistor. The circuit generates 'clock pulses' - simply a regular sequence of logic LO and logic HI. The capacitor charges and discharges through the resistor. As the capacitor charges to a certain level, the inverter's input goes HI and its output goes LO. This this causes the capacitor to start discharging. When its voltage gets low enough, the inverter output goes back to HI and the cycle starts again. By increasing the resistance or increasing the capacitance, the pulses can be generated more slowly. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Coefficient of cubical expansion [/COLOR][/SIZE][/FONT][/B] The increase in volume of a substance per unit original volume per degree rise in temperature is called its coefficient of cubical expansion. The SI unit of coefficient of cubical expansion is K-1. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Coefficient of linear expansion[/COLOR][/SIZE][/FONT][/B] The increase in length per unit original length per degree rise in temperature is called the coefficient of linear expansion. The SI unit of the coefficient of linear expansion is K-1. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Coherent[/COLOR][/SIZE][/FONT][/B] A light wave whose parts are all in phase with each other. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Collision[/COLOR][/SIZE][/FONT][/B] An interaction between moving objects that lasts for a certain time. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Comet[/COLOR][/SIZE][/FONT][/B] A comet is a small body orbiting our Sun, usually at great distance from Earth and with a highly elliptical orbit. They are composed of 'ices' and dust. As a comet approaches the inner solar system, the heat of the Sun vapourises volatile material from the surface and pushes the material directly away from the Sun. This gives rise to the 'ion tail', usually a ghostly blue colour and quite straight, it always points directly away from the Sun and has nothing to do with the direction of motion of the comet. A second tail exists, usually white and curved. This is dust which falls off the comet and is left in track of its orbit. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Component[/COLOR][/SIZE][/FONT][/B] The part of a velocity, acceleration, or force that is along one particular coordinate axis. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Compression[/COLOR][/SIZE][/FONT][/B] A part of a longitudinal wave in which the density of the particles of the medium is higher than the normal density is called a compression. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Compressive stress[/COLOR][/SIZE][/FONT][/B] A force that tends to compress the surface as the earth's plates move into each other. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Concave[/COLOR][/SIZE][/FONT][/B] Describes a surface that is hollowed out like a cave. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Condensation (sound)[/COLOR][/SIZE][/FONT][/B] A compression of gas molecules; a pulse of increased density and pressure that moves through the air at the speed of sound. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Condensation (water vapor)[/COLOR][/SIZE][/FONT][/B] Where more vapor or gas molecules are returning to the liquid state than are evaporating. [FONT="Comic Sans MS"][B][SIZE="4"][COLOR="Blue"]Condensation nuclei [/COLOR][/SIZE][/B][/FONT] Tiny particles such as tiny dust, smoke, soot, and salt crystals that are suspended in the air on which water condenses condensation point the temperature at which a gas or vapor changes back to a liquid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Condensation point[/COLOR][/SIZE][/FONT][/B] The temperature at which a gas or vapor changes back to a liquid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Conductor[/COLOR][/SIZE][/FONT][/B] A material that allows electricity to flow easily through it. Copper, for example is a good conductor. Good conductors have a very low resistance. See also insulators and semi-conductors. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Conduction [/COLOR][/SIZE][/FONT][/B] The transfer of heat from a region of higher temperature to a region of lower temperature by increased kinetic energy moving from molecule to molecule. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Constructive interference [/COLOR][/SIZE][/FONT][/B] The condition in which two waves arriving at the same place, at the same time and in phase, add amplitudes to create a new wave. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Consumer Unit[/COLOR][/SIZE][/FONT][/B] Commonly known as the fusebox, the consumer unit is the part of the meter board which separates the incoming electrical supply into the various lighting and ring main circuits. Each of these circuits is protected by either a fuse or miniature circuit breaker (MCB). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Control rods[/COLOR][/SIZE][/FONT][/B] Rods inserted between fuel rods in a nuclear reactor to absorb neutrons and thus control the rate of the nuclear chain reaction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Convection [/COLOR][/SIZE][/FONT][/B] The transfer of heat from one place to another by the motion of a gas or a liquid across the heated surface. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Convex[/COLOR][/SIZE][/FONT][/B] Describes a surface that bulges outward. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Conventional current[/COLOR][/SIZE][/FONT][/B] Opposite to electron current-that is, considers an electric current to consist of a drift of positive charges that flow from the positive terminal to the negative terminal of a battery. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Coulomb [/COLOR][/SIZE][/FONT][/B] Unit used to measure quantity of electric charge; equivalent to the charge resulting from the transfer of 6.24 billion particles such as the electron. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Coulomb's law[/COLOR][/SIZE][/FONT][/B] Relationship between charge, distance, and magnitude of the electrical force between two bodies. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Covalent bond[/COLOR][/SIZE][/FONT][/B] A chemical bond formed by the sharing of a pair of electrons. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Covalent compound[/COLOR][/SIZE][/FONT][/B] Chemical compound held together by a covalent bond or bonds. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Crest[/COLOR][/SIZE][/FONT][/B] The point of maximum positive displacement on a transverse wave is called a crest. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Critical angle [/COLOR][/SIZE][/FONT][/B] Limit to the angle of incidence when all light rays are reflected internally. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Critical mass [/COLOR][/SIZE][/FONT][/B] Mass of fissionable material needed to sustain a chain reaction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Current[/COLOR][/SIZE][/FONT][/B] Electrical current is the rate of flow of electrical charge round a circuit. It is measured in amperes and should be measured in series with an ammeter. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Curvilinear Motion[/COLOR][/SIZE][/FONT][/B] The motion of a body along a curved path is called curvilinear motion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Cycle [/COLOR][/SIZE][/FONT][/B] A complete vibration. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Damping[/COLOR][/SIZE][/FONT][/B] The dissipation of a vibration's energy into heat energy, or the frictional force that causes the loss of energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Deceleration[/COLOR][/SIZE][/FONT][/B] Deceleration basically means slowing down - reducing speed. A negative answer for an acceleration would actually be a deceleration. Like acceleration, deceleration is also measured in ms-2. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Decibel (dB) Scale[/COLOR][/SIZE][/FONT][/B] The decibel scale is used to measure the volume (intensity or loudness) of sound. The abbreviation for this unit is dB. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Decoder[/COLOR][/SIZE][/FONT][/B] The decoder section of a radio essentially removes the carrier wave from the modulated signal, leaving only the audio wave which is then amplified. In TVs there are two separate decoders - one for the picture and one for the sound. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Deflection Plates[/COLOR][/SIZE][/FONT][/B] Deflection plates are used to direct the electron beam to all parts of the cathode ray tube of an oscilloscope. There are two sets of plates, one set for controlling horizontal movement of the beam and the other set for vertical movement. Each set of plates controls the beam by having a certain voltage applied across the plates. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Destructive interference[/COLOR][/SIZE][/FONT][/B] The condition in which two waves arriving at the same point at the same time out of phase add amplitudes to create zero total disturbance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Dew point temperature[/COLOR][/SIZE][/FONT][/B] The temperature at which condensation begins. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Dew[/COLOR][/SIZE][/FONT][/B] Condensation of water vapor into droplets of liquid on surfaces. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Diffraction[/COLOR][/SIZE][/FONT][/B] Diffraction is a wave phenomenon - i.e. all types of wave can diffract. Diffraction means the bending of wave (change in direction) and it occurs whenever a wave passes near to an obstacle. Longer wavelength waves diffract through a greater angle than shorter wavelength waves. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Diffuse reflection[/COLOR][/SIZE][/FONT][/B] Light rays reflected in many random directions, as opposed to the parallel rays reflected from a perfectly smooth surface such as a mirror. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Digital[/COLOR][/SIZE][/FONT][/B] Digital can refer to electronic signals or to components of an electronic system. Digital signals have only two voltage levels, described as 'HI' and 'LO', or 'OFF' and 'ON'. In a real component, 'HI' might be represented by +5V d.c. and 'LO' by 0V d.c. A digital component is one which works with only digital signals. Here are some examples of digital components: LED (output), photodiode (input), switch (input). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Diode [/COLOR][/SIZE][/FONT][/B] A diode is a semi-conductor device. Diodes will allow current to pass through them in only one direction. [IMG]http://www.users.zetnet.co.uk/computing/MainPage/SecDepts/Physics/Resources/Glossary/LED.gif[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Direct current[/COLOR][/SIZE][/FONT][/B] An electrical current that always moves in one direction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Direct proportion[/COLOR][/SIZE][/FONT][/B] When two variables increase or decrease together in the same ratio (at the same rate). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Dispersion [/COLOR][/SIZE][/FONT][/B] The effect of spreading colors of light into a spectrum with a material that has an index of refraction that varies with wavelength. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Displacement[/COLOR][/SIZE][/FONT][/B] The change in the position of an object in a particular direction is called displacement. Displacement may also be defined as the shortest distance between the initial and final position of a moving body. It is a vector quantity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Distance[/COLOR][/SIZE][/FONT][/B] The actual length of the path traveled by a body irrespective of the direction is called the distance traveled. It is a scalar quantity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Doppler effect[/COLOR][/SIZE][/FONT][/B] An apparent shift in the frequency of sound or light due to relative motion between the source of the sound or light and the observer. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Dose Equivalent[/COLOR][/SIZE][/FONT][/B] This is the biological risk due to exposure to radiation. The SI unit of dose equivalent is the sievert (Sv). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Double Insulation[/COLOR][/SIZE][/FONT][/B] An electrical appliance which is double insulated does not have an earth wire fitted. The appliance is designed in such a way that the electrical parts can never come into contact with the outer casing of the device. Common double insulated appliances are hair dryers, radios and cassette players. A wet double insulated appliance is exceptionally dangerous - water is a good conductor of electricity and will easily reach the live electrical components within the case. Any human user touching the casing will then receive an electric shock. It is important to note that the human conductivity is increased when hands are wet, allowing a greater current to flow through the casualty. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Drag[/COLOR][/SIZE][/FONT][/B] Drag is a type of friction force usually associated with movement through a fluid like air or water. Drag forces generally increase at high speeds. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Driving force[/COLOR][/SIZE][/FONT][/B] An external force that pumps energy into a vibrating system. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Dynamo[/COLOR][/SIZE][/FONT][/B] A device (a traducer) which converts kinetic energy into electrical energy. Dynamos are often used to produce a.c. electricity on a push-bike. Unlike a full-blown generator, the rotor coil is replaced with rotating permanent magnets. These magnets rotate near to the stator coil, (wrapped around a soft iron core) and cause a small current to flow (via electromagnetic induction). |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Echo [/COLOR][/SIZE][/FONT][/B] A reflected sound that can be distinguished from the original sound, which usually arrives 0.1 sec or more after the original sound. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Efficiency[/COLOR][/SIZE][/FONT][/B] Efficiency is defined as 'Useful Energy Out' / 'Total Energy In'. It is a fraction, sometimes written as a percentage. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Elastic strain [/COLOR][/SIZE][/FONT][/B] An adjustment to stress in which materials recover their original shape after a stress is released. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electric circuit [/COLOR][/SIZE][/FONT][/B] Consists of a voltage source that maintains an electrical potential, a continuous conducting path for a current to follow, and a device where work is done by the electrical potential; a switch in the circuit is used to complete or interrupt the conducting path. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electric current [/COLOR][/SIZE][/FONT][/B] Electric current is the flow (movement) of electric charge. The SI unit of electric current is the Ampere (A), which is equal to a flow of one Coulomb of charge per second. Electric current is measured using an ammeter. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electric dipole [/COLOR][/SIZE][/FONT][/B] An object that has an imbalance between positive charge on one side and negative charge on the other; an object that will experience a torque in an electric field. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electric field lines[/COLOR][/SIZE][/FONT][/B] A map of an electric field representing the direction of the force that a test charge would experience; the direction of an electric field shown by lines of force. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electric generator [/COLOR][/SIZE][/FONT][/B] A mechanical device that uses wire loops rotating in a magnetic field to produce electromagnetic induction in order to generate electricity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electric potential energy[/COLOR][/SIZE][/FONT][/B] Potential energy due to the position of a charge near other charges. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrical conductors[/COLOR][/SIZE][/FONT][/B] Materials that have electrons that are free to move throughout the material; for example, metals. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrical energy[/COLOR][/SIZE][/FONT][/B] A form of energy from electromagnetic interactions; one of five forms of energy-mechanical, chemical, radiant, electrical, and nuclear. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrical force[/COLOR][/SIZE][/FONT][/B] A fundamental force that results from the interaction of electrical charge and is billions and billions of times stronger than the gravitational force. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrical insulators[/COLOR][/SIZE][/FONT][/B] Electrical nonconductors, or materials that obstruct the flow of electric current. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrical nonconductors[/COLOR][/SIZE][/FONT][/B] Materials that have electrons that are not moved easily within the material-for example, rubber; electrical nonconductors are also called electrical insulators. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrical resistance[/COLOR][/SIZE][/FONT][/B] The property of opposing or reducing electric current. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrolyte [/COLOR][/SIZE][/FONT][/B] Water solution of ionic substances that conducts an electric current. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electromagnet[/COLOR][/SIZE][/FONT][/B] An electromagnet is a solenoid with an iron core inserted into it. If a current flows in the coil, a magnetic field is generated. All the randomly oriented domains of the iron core then align in the presence of the field of the solenoid. Thus, the core greatly enhances the strength of the electromagnet. [IMG]http://www.bbc.co.uk/schools/ks3bitesize/science/images/sci_dia_79.gif[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electromagnetic induction[/COLOR][/SIZE][/FONT][/B] Process in which current is induced by moving a loop of wire in a magnetic field or by changing the magnetic field. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electromagnetic Spectrum[/COLOR][/SIZE][/FONT][/B] This includes Gamma, X-rays, Ultraviolet, Visible, Infra-red, Microwave and Radio - in order of increasing wavelength. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electromagnetic waves[/COLOR][/SIZE][/FONT][/B] The waves which are due to oscillating electrical and magnetic fields and do not need any material medium for their propagation are called electromagnetic waves. These waves can, however, travel through material medium also. Light waves, radio waves are examples of electromagnetic waves. All electromagnetic waves travel in vacuum with a speed of 3×10 8 m/s. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electron configuration [/COLOR][/SIZE][/FONT][/B] The arrangement of electrons in orbits and sub-orbits about the nucleus of an atom. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electron current [/COLOR][/SIZE][/FONT][/B] Opposite to conventional current; that is, considers electric current to consist of a drift of negative charges that flows from the negative terminal to the positive terminal of a battery. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electron pair [/COLOR][/SIZE][/FONT][/B] A pair of electrons with different spin quantum numbers that may occupy an orbital. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electron volt[/COLOR][/SIZE][/FONT][/B] The energy gained by an electron moving across a potential difference of one volt; equivalent to 1.60 x 10^-19 Joules. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electron[/COLOR][/SIZE][/FONT][/B] Electrons are sub-atomic particles. They carry a negative electrical charge (qe=-1.602 x 10-19 C). They have a mass of me = 9.110 x 10-31 kg. Beams of electrons are used in TV sets where they are called cathode rays. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electro negativity. [/COLOR][/SIZE][/FONT][/B] The comparative ability of atoms of an element to attract bonding electrons. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electronic System[/COLOR][/SIZE][/FONT][/B] An electronic system can simply be considered as consisting of three parts: input, process and output. Input devices include microphones and LDRs, thermistors and switches. Process sections can be made from one or more transistors, perhaps built into logic gates or computer chips. The output section will consist of one or more output devices, for example, a buzzer, LED, lamp, CRT. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Electrostatic charge [/COLOR][/SIZE][/FONT][/B] An accumulated electric charge on an object from a surplus or deficiency of electrons. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Element [/COLOR][/SIZE][/FONT][/B] A pure chemical substance that cannot be broken down into anything simpler by chemical or physical means. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Energy [/COLOR][/SIZE][/FONT][/B] The capacity of a body to do work is called its energy. Energy is a scalar quantity. The SI unit of energy is Joule.Energy can not be created or destroyed, but can be changed from one form to another. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Escape Velocity[/COLOR][/SIZE][/FONT][/B] The minimum velocity with which an object must be thrown upwards so as to overcome the gravitational pull and escape into space, is called escape velocity (V esc ). The escape velocity depends upon the mass and radius of the planet/star. It does not depend upon the mass of the body thrown up. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Equilibrium[/COLOR][/SIZE][/FONT][/B] A state in which an object's momentum and angular momentum are constant. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Evaporation[/COLOR][/SIZE][/FONT][/B] Process of more molecules leaving a liquid for the gaseous state than returning from the gas to the liquid. It can occur at any given temperature from the surface of a liquid. Evaporation takes place only from the surface of the liquid. Evaporation causes cooling. Evaporation is faster if the surface of the liquid is large, the temperature is higher and the surrounding atmosphere does not contain a large amount of vapor of the liquid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Eyepiece Lens[/COLOR][/SIZE][/FONT][/B] The lens on a telescope (or microscope) which the observer places his or her eye next to. The eyepiece's sole funciton is to magnify the image. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Farad [/COLOR][/SIZE][/FONT][/B] The farad (F) is the SI Unit of capacitance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fahrenheit scale of temperature[/COLOR][/SIZE][/FONT][/B] On the Fahrenheit scale, the ice point, the ice point (lower fixed point) is taken as 32? F and the steam point (upper fixed point) is taken as 212 deg F. The interval between these two points is divided into 180 equal divisions. Thus, unit division on the Fahrenheit scale is 1deg F. The temperatures on the Celsius scale and the Fahrenheit scale are related by the relationship, C/100 = (F - 32) / 180. The temperature of a normal healthy person is 37 deg C or 98.6 deg F. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fibrescope[/COLOR][/SIZE][/FONT][/B] Fibrescope are sometimes called endoscopes. A flexible fiber-optic instrument used to view an object or area, such as a body cavity, that would otherwise be inaccessible. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Field[/COLOR][/SIZE][/FONT][/B] A property of a point in space describing the forces that would be exerted on a particle if it was there. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Filament Lamp[/COLOR][/SIZE][/FONT][/B] These lamps rely on an incandescent metal filament to produce light. The interior of the lamp is filled with an inert gas in order to stop the filament from corroding. An electrical current, passed through the filament makes it extremely hot. When sufficiently hot, the filament itself will emit light radiation. Tungsten metal is chosen for the filament due to its high melting point of about 3956 Celsius. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]First law of motion [/COLOR][/SIZE][/FONT][/B] Every object remains at rest or in a state of uniform straight-line motion unless acted on by an unbalanced force. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fission Process[/COLOR][/SIZE][/FONT][/B] This usually refers to nuclear fission, where an atomic nucleus splits apart into smaller pieces. Fission should not be confused with fusion. When a heavy, unstable nucleus undergoes fission, energy is released as heat. In nuclear power stations, uranium is often used as the fissile material, where a nuclear chain reaction is controlled to release energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Flex [/COLOR][/SIZE][/FONT][/B] The flex allows electrical current to flow into domestic appliances from the mains socket. The flex should be correctly wired to a plug. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fluids[/COLOR][/SIZE][/FONT][/B] Matter that has the ability to flow or be poured; the individual molecules of a fluid are able to move, rolling over or by one another. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fluid friction[/COLOR][/SIZE][/FONT][/B] A friction force in which at least one of the object is a fluid (i.e. either a gas or a liquid). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fluorescent Lamps[/COLOR][/SIZE][/FONT][/B] These lamps produce light by passing electrical current through a mercury vapour at low pressure. The electrical current excites ("energises") the electrons of the mercury atoms. These electrons quickly give up their energy as light. The light which is produced is invisible ultra-violet and would be useless. To get round this problem, the inside of the tube is coated with fluorescent paint, which converts U.V. light to visible light. Fluorescent lamps are more efficient than filament lamps as they waste less energy as heat. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Focal Length[/COLOR][/SIZE][/FONT][/B] The focal length of lens is measured in meters. It is the distance from the centre of the lens to the point at which rays passing through the lens meet (i.e. focus). It is related to lens power. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Force[/COLOR][/SIZE][/FONT][/B] Forces can cause an object to speed up, slow down, change direction or change shape (if they are unbalanced). Forces are either push forces or pull forces. Force is a vector quantity.The SI unit of force is the newton,denoted by N. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Force of gravitation [/COLOR][/SIZE][/FONT][/B] The force with which two objects attract each other by virtue of their masses is called the force of gravitation. The force of attraction acts even if the two objects are not connected to each other. It is an action-at-a-distance force. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fossil Fuel [/COLOR][/SIZE][/FONT][/B] Fossil fuels are coal, oil and gas. They are non-renewable resources. Fossil fuels come from ancient remains of plants and animals, compressed and heated over many millenia. The combustion of fossil fuels is now (nearly) universally accepted as causing global warming. They are well known to produce acid rain. Most of the world's energy is still produced from fossil fuel. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fracture strain[/COLOR][/SIZE][/FONT][/B] An adjustment to stress in which materials crack or break as a result of the stress. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Free fall [/COLOR][/SIZE][/FONT][/B] The motion of a body towards the earth when no other force except the force of gravity acts on it is called free fall. All freely falling bodies are weightless. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Freezing point[/COLOR][/SIZE][/FONT][/B] The temperature at which a phase change of liquid to solid takes place; the same temperature as the melting point for a given substance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Frequency[/COLOR][/SIZE][/FONT][/B] The frequency of a regular event is the number of times the event occurs in a given time.The SI unit of frequency is the hertz (Hz) (equivalent to 'per second' or s-1). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Frequency (of waves) [/COLOR][/SIZE][/FONT][/B] The number of waves produced per second is called its frequency. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Frequency (of oscillations) [/COLOR][/SIZE][/FONT][/B] The number of oscillations made by an oscillating body per second is called the frequency. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Frequency Modulation[/COLOR][/SIZE][/FONT][/B] Frequency modulation refers to the changing of the frequency of a radio-frequency or microwave frequency carrier wave. The other method of modulation is called amplitude modulation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Friction[/COLOR][/SIZE][/FONT][/B] Friction is a force which tends to make moving objects slow down. Friction also prevents objects from slipping over one another. Friction due to fluid flow is called drag. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fridge [/COLOR][/SIZE][/FONT][/B] A fridge is an example of a heat pump. It extracts heat energy from inside the fridge cabinet and releases it into the room. The basic principle relies on the latent heat of vaporisation of a coolant liquid. The coolant is evaporated within the pipes inside the cabinet - the heat required for this is taken from the cabinet itself, with the result that the cabinet becomes cooler. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fuel rod [/COLOR][/SIZE][/FONT][/B] Long zirconium alloy tubes containing fissionable material for use in a nuclear reactor. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fundamental charge[/COLOR][/SIZE][/FONT][/B] Smallest common charge known; the magnitude of the charge of an electron and a proton, which is 1.60 x 10^-19 coulomb. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fundamental frequency[/COLOR][/SIZE][/FONT][/B] The lowest frequency (longest wavelength) that can set up standing waves in an air column or on a string. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fundamental properties[/COLOR][/SIZE][/FONT][/B] A property that cannot be defined in simpler terms other than to describe how it is measured; the fundamental properties are length, mass, time, and charge. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fuse[/COLOR][/SIZE][/FONT][/B] A fuse, where fitted, is designed to protect the flex (and not the appliance) from current overload and the associated risk of fire. The fuse rating should always be less than that of the flex which it is protecting. This will make sure that it blows before the flex melts. If the fuse in the plug blows, it is likely to be because of a fault in the appliance which is drawing too much current. The fuse (and switch) should always be connected to the live wire in a plug. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Fusion[/COLOR][/SIZE][/FONT][/B] A nuclear reaction in which two nuclei stick together to form one bigger nucleus. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]g [/COLOR][/SIZE][/FONT][/B] Symbol representing the acceleration of an object in free fall due to the force of gravity; its magnitude is 9.80 m/sec^2 (32.0 ft/sec^2). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Galaxy[/COLOR][/SIZE][/FONT][/B] A grouping of about approximately 100 billion stars, held together by their own gravity. We live in the Milky Way galaxy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gamma (g) Radiation[/COLOR][/SIZE][/FONT][/B] g (gamma) radiation is high frequency electromagnetic radiation. It is a part of the electromagnetic spectrum. Gamma radiation carries no mass, no charge, travels at the speed of light. (It can be thought of as being made of particles called photons or as being a wave). It can be stopped by several centimetres of lead or a few metres of concrete. Gamma radiation is an ionising radiation, but is not as strongly ionising as a radiation. It is released during the disintegration of an unstable nucleus. For the purposes of treating cancer, medical gamma rays from cobalt-60 are used. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gamma Camera[/COLOR][/SIZE][/FONT][/B] This is a device used to detect the gamma radiation from a patient during an examination using a radioactive tracer. Since gamma radiation passes straight through most materials, it is not possible to build a camera with glass lenses or mirrors. Instead an array of holes drilled in a thick layer of lead is placed between the actual gamma detectors and the patient. This allows an image to be built up. Scintillation counters are used to detect the radiation after it has passed through the holes in the commutator. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gases[/COLOR][/SIZE][/FONT][/B] A phase of matter composed of molecules that are relatively far apart moving freely in a constant, random motion and have weak cohesive forces acting between them, resulting in the characteristic indefinite shape and indefinite volume of a gas. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gas Discharge Lamps[/COLOR][/SIZE][/FONT][/B] These lamps produce light by passing electrical current through a gas at low pressure. The electrical current excites ("energises") the electrons of the atoms in the gas. These electrons quickly give up their energy as light. Sodium is often used (in street lights) or an inert gas for colourful advertising lights. Discharge lamps are more efficient than filament lamps as they waste less energy as heat. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Geiger-Muller tube[/COLOR][/SIZE][/FONT][/B] This is a device used to detect the presence of radiation. It relies on ionisation to produce tiny bursts of current which can be counted by a rate meter. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Geostationary[/COLOR][/SIZE][/FONT][/B] 'Geostationary' refers to a satellite of planet Earth. Such a satellite will appear to hover above the surface of the Earth, since it is placed in an orbit with a period of 24 hours. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Geothermal Energy[/COLOR][/SIZE][/FONT][/B] This is a renewable energy resource, unlike fossil fuels. In some parts of the world, hot subsurface rock heats water which reaches the surface and can be used for heating or electrical power generation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Generator[/COLOR][/SIZE][/FONT][/B] A machine which uses motion to produce electrical energy. Sometimes called an alternator. A generator is like a dynamo, but with the permanent rotor magnets replaced with (d.c) rotor coils (electromagnets). The stator coils have an a.c. induced within them. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gold Grain[/COLOR][/SIZE][/FONT][/B] Radioactive gold grains are used in the treatment of cancer. Gold (which is unreactive) doped with radioactive (gamma emitting) nuclei is implanted in a patient, near or in a tumour. The radiation will destroy or damage cells near the grain. The radioactive material chosen will have a short half-life so that the grain's activity level will drop to background levels after several days. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gram-atomic weight[/COLOR][/SIZE][/FONT][/B] The mass in grams of one mole of an element that is numerically equal to its atomic weight. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gram-formula weight.[/COLOR][/SIZE][/FONT][/B] The mass in grams of one mole of a compound that is numerically equal to its formula weight. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gram-molecular weight.[/COLOR][/SIZE][/FONT][/B] The gram-formula weight of a molecular compound. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gravity[/COLOR][/SIZE][/FONT][/B] A general term for the phenomenon of attraction between things having mass. The attraction between our planet and a human-sized object causes the object to fall. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gravitational constant G[/COLOR][/SIZE][/FONT][/B] The constant G which appears in the equation for Newton's law of gravitation is called the universal constant of gravitation or the gravitational constant. Numerically it is equal to the force of gravitation, which acts between two bodies of mass 1kg each separated by a distance of 1m. The value of G is 6.67×10-11 Nm²/kg². [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gravitational Field [/COLOR][/SIZE][/FONT][/B] The Earth generates a gravitational field which attracts all other masses. It is a called a force field - the word field means that the force changes as you move away from the surface of the Earth (in fact the force becomes steadily less as you move away from the surface of the Earth). It is the combined mass of all particles on Earth which cause the Earth's gravitational field. The strength of the field is measured in Nkg-1. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Gravitational Potential Energy[/COLOR][/SIZE][/FONT][/B] Gravitational potential energy is energy an object possesses because of its position in a gravitational field. If a mass is lifted up then its potential energy is given as follows: Ep = mgh Ep is the potential energy m is the mass in kilograms g is the strength of the gravitational field (10ms-2 on Earth) h is the height through which the object is lifted [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Greenhouse effect[/COLOR][/SIZE][/FONT][/B] The process of increasing the temperature of the lower parts of the atmosphere through redirecting energy back toward the surface; the absorption and reemission of infrared radiation by carbon dioxide, water vapor, and a few other gases in the atmosphere. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ground state[/COLOR][/SIZE][/FONT][/B] Energy state of an atom with electrons at the lowest energy state possible for that atom. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Half-life [/COLOR][/SIZE][/FONT][/B] The half-life of a radioactive material is the time taken for its activity level to drop by a half. Half-life is measured using any unit of time (seconds, hours). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Heat[/COLOR][/SIZE][/FONT][/B] Heat is a form of energy, which makes a body hot or cold. Heat is measured by the temperature-effect it produces in any material body. The SI unit of heat is Joule( J). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Heat Energy[/COLOR][/SIZE][/FONT][/B] Heat is a form of energy and is not to be confused with temperature. There is no such thing as 'cold energy'. At the molecular level, heat energy is transferred from particle to particle by vibration (this is called conduction). A particle vibrating violently can be said to have a lot of heat energy. As well as by conduction, heat can also be transferred by convection or radiation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Heater[/COLOR][/SIZE][/FONT][/B] The operation of a bar heater is very similar indeed to a filament lamp. The difference is in the thickness of the 'filament' or element of the heater. Curiously, heaters operate at a lower temperature than lamps, but produce far more heat - as infra-red radiation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Heat Pump[/COLOR][/SIZE][/FONT][/B] This is a device which can move heat energy from a colder object to a hotter one, but requiring an external energy source to do it. A fridge is an example of a heat pump. Due to the second law of thermodynamics, a heat pump can never be 100% efficient. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Heat death of the Universe[/COLOR][/SIZE][/FONT][/B] Time at which no work will be able to be done because all heat energy in the Universe will be evenly distributed (so that no further increase in entropy is possible). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Heisenberg uncertainty principle [/COLOR][/SIZE][/FONT][/B] You cannot measure both the exact momentum and the exact position of a subatomic particle at the same time-when the more exact of the two is known, the less certain you are of the value of the other. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Hertz[/COLOR][/SIZE][/FONT][/B] Unit of frequency; equivalent to one cycle per second. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Horsepower[/COLOR][/SIZE][/FONT][/B] Measurement of power defined as a power rating of 550 ft-lb/sec. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Hypothesis[/COLOR][/SIZE][/FONT][/B] A tentative explanation of a phenomenon that is compatible with the data and provides a framework for understanding and describing that phenomenon. [B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]I[/COLOR][/SIZE][/FONT][/CENTER][/B] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ice-point[/COLOR][/SIZE][/FONT][/B] It is the melting point of pure melting ice under 1 Atmospheric pressure. The ice point is taken as the lower fixed point ( 0 deg C or 32 deg F ) for temperature scales. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Image[/COLOR][/SIZE][/FONT][/B] A place where an object appears to be, because the rays diffusely reflected from any given point on the object have been bent so that they come back together and then spread out again from the image point, or spread apart as if they had originated from the image. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Impulse[/COLOR][/SIZE][/FONT][/B] The impulse acting on a body is equal to the product of the force acting on the body and the time for which it acts. If the force is variable, the impulse is the integral of Fdt from t0 to t1. The impulse of a force acting for a given time interval is equal to change in momentum produced over that interval. J=m(v-u), assuming that the mass m remains constant while the velocity changes from v to u. The SI units of impulse are kg m/s. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Impulsive force[/COLOR][/SIZE][/FONT][/B] The force which acts on a body for a very short time but produces a large change in the momentum of the body is called an impulsive force. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Incandescent[/COLOR][/SIZE][/FONT][/B] Matter emitting visible light as a result of high temperature for example, a light bulb, a flame from any burning source, and the sun are all incandescent sources because of high temperature. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Incident ray[/COLOR][/SIZE][/FONT][/B] Line representing the direction of motion of incoming light approaching a boundary. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Independence[/COLOR][/SIZE][/FONT][/B] The lack of any relationship between two random events. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Index of refraction[/COLOR][/SIZE][/FONT][/B] The ratio of the speed of light in a vacuum to the speed of light in a material. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Induction[/COLOR][/SIZE][/FONT][/B] The production of an electric field by a changing magnetic field, or vice-versa. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Inert [/COLOR][/SIZE][/FONT][/B] A chemical element is inert if it does not react with anything. Examples are helium, neon, argon, krypton, xenon and radon. Inert gases can be used in filament lamps to protect the filament from destruction due corrosion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Inertia [/COLOR][/SIZE][/FONT][/B] The property of matter that causes it to resist any change in its state of rest or of uniform motion. There are three kinds of inertia- inertia of rest, inertia of motion and inertia of direction. The mass of a body is a measure of its inertia.The SI unit for inertia is the kilogram. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Inertial frame[/COLOR][/SIZE][/FONT][/B] A frame of reference that is not accelerating, one in which Newton's first law is true. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Infrasonic[/COLOR][/SIZE][/FONT][/B] Sound waves having too low a frequency to be heard by the human ear; sound having a frequency of less than 20 Hz. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Infrared[/COLOR][/SIZE][/FONT][/B] Infrared radiation is invisible. It is a form of electromagnetic radiation, with a wavelength just longer than that of visible red light. Infrared light is use in telecommunications (via optical fibres). It is used in medicine to diagnose illness (thermograms) and accelerate healing in physiotherapy. Infrared radiation can be thought of as 'heat rays'. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Input Device[/COLOR][/SIZE][/FONT][/B] The first part of an electronic system, an input device typically processes requests from a human user. For example in a CD player, the 'ON' button and volume controls (potentiometer) are all input devices. Other input devices include switches, thermistors, LDRs, photodiodes. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Instantaneous[/COLOR][/SIZE][/FONT][/B] This means an event which occurs over a very short (infinitesimal) period of time. It usually refers to speed, i.e. instantaneous speed as opposed to average speed. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Instantaneous Speed[/COLOR][/SIZE][/FONT][/B] The speed at any particular stage or time during a journey. Instantaneous speed can be calculated by measuring short distances and time intervals. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Insulator[/COLOR][/SIZE][/FONT][/B] A material which does not usually conduct electricity. Air, for example is an insulator. Insulators have a very high (ideally infinite) resistance. Given a suitably high voltage, insulators can be forced to conduct ,for example lightning during a thunderstorm. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Insulation [/COLOR][/SIZE][/FONT][/B] A nonconducting material designed to reduce the transfer of energy or electric current between two materials. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Intensity[/COLOR][/SIZE][/FONT][/B] A measure of the energy carried by a wave. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Interference[/COLOR][/SIZE][/FONT][/B] Phenomenon of light where the relative phase difference between two light waves produces light or dark spots, a result of light's wavelike nature. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Intermolecular forces[/COLOR][/SIZE][/FONT][/B] Forces of interaction between molecules. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Internal energy[/COLOR][/SIZE][/FONT][/B] Sum of all the potential energy and all the kinetic energy of all the molecules of an object. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Invariant[/COLOR][/SIZE][/FONT][/B] A quantity that does not change when transformed. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Inverse proportion[/COLOR][/SIZE][/FONT][/B] The relationship in which the value of one variable increases while the value of the second variable decreases at the same rate (in the same ratio). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Inverter (NOT gate)[/COLOR][/SIZE][/FONT][/B] A processing device within an electronic system, the NOT gate is a single input logic gate which 'inverts' its input. A logic 'HI' input will become a logic 'LOW' output and visa-versa. Here is the truth table: A Z 0 1 1 0 [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ion[/COLOR][/SIZE][/FONT][/B] An electrically charged atom or molecule. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ionization[/COLOR][/SIZE][/FONT][/B] Process of forming ions from molecules. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ionized[/COLOR][/SIZE][/FONT][/B] An atom or a particle that has a net charge because it has gained or lost electrons. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Isostasy[/COLOR][/SIZE][/FONT][/B] A balance or equilibrium between adjacent blocks of crust. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Isotope[/COLOR][/SIZE][/FONT][/B] One of the possible varieties of atoms of a given element, having a certain number of neutrons. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]J[/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Joule [/COLOR][/SIZE][/FONT][/B] Metric unit used to measure work and energy; can also be used to measure heat; equivalent to newton-meter. [B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]K[/COLOR][/SIZE][/FONT][/CENTER][/B] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kelvin[/COLOR][/SIZE][/FONT][/B] The kelvin is the SI Unit of absolute temperature. 273.15 K is the same as 0 Celsius and 373.15 K is the same as 100 Celsius. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kepler's first law[/COLOR][/SIZE][/FONT][/B] Relationship in planetary motion that each planet moves in an elliptical orbit, with the sun located at one focus. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kepler's laws of planetary motion[/COLOR][/SIZE][/FONT][/B] The three laws describing the motion of the planets. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kepler's second law[/COLOR][/SIZE][/FONT][/B] Relationship in planetary motion that an imaginary line between the sun and a planet moves over equal areas of the ellipse during equal time intervals. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kepler's third law[/COLOR][/SIZE][/FONT][/B] Relationship in planetary motion that the square of the period of an orbit is directly proportional to the cube of the radius of the major axis of the orbit. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kilo calorie[/COLOR][/SIZE][/FONT][/B] The amount of energy required to increase the temperature of one kilogram of water one degree Celsius: equivalent to 1,000 calories. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kilogram[/COLOR][/SIZE][/FONT][/B] The kilogram is the SI unit of mass. It is defined as the mass of a particular cylinder of platinum. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kinetic Energy[/COLOR][/SIZE][/FONT][/B] Energy possessed by a body by the virtue of its motion is called kinetic energy. Kinetic energy = 1/2 m v². [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Kinetic friction[/COLOR][/SIZE][/FONT][/B] A friction force between surfaces that are slipping past each other. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]L[/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Lamp[/COLOR][/SIZE][/FONT][/B] A device intended to produce light energy. Modern lamps convert electrical energy to light energy via one of two main mechanisms - the filament lamp or the gas discharge lamp. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Laser[/COLOR][/SIZE][/FONT][/B] The word laser was originally an abbreviation for Light Amplification by the Stimulated Emission of Radiation. Lasers have countless applications, many in medicine and communications. Lasers produce light which is monochromatic, coherent and tightly focussed. Lasers are used in the technique of photocoagulation (used to treat retinae). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Latent heat of vaporization [/COLOR][/SIZE][/FONT][/B] The heat absorbed when one gram of a substance changes from the liquid phase to the gaseous phase, or the heat released when one gram of gas changes from the gaseous phase to the liquid phase. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Latent heat of fusion[/COLOR][/SIZE][/FONT][/B] The quantity of heat required to convert one unit mass of a substance from solid to the liquid state at its melting point (without any change in its temperature) is called its latent heat of fusion (L). The SI unit of latent heat of fusion is J kg-1. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Latent heat[/COLOR][/SIZE][/FONT][/B] Latent heat, or hidden heat, is heat that is taken up and stored when a substance changes state from a solid to a liquid, from a liquid to a gas, or from a solid directly to a gas. It cannot be measured by a thermometer. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Law of Conservation of Energy[/COLOR][/SIZE][/FONT][/B] The law of conservation of energy states that energy may neither be created nor destroyed. Therefore the sum of all the energies in the system is a constant. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Law of conservation of mass [/COLOR][/SIZE][/FONT][/B] Same as law of conservation of matter; mass, including single atoms, is neither created nor destroyed in a chemical reaction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Law of conservation of matter [/COLOR][/SIZE][/FONT][/B] Matter is neither created nor destroyed in a chemical reaction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Law of conservation of momentum [/COLOR][/SIZE][/FONT][/B] The total momentum of a group of interacting objects remains constant in the absence of external forces. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Light [/COLOR][/SIZE][/FONT][/B] Anything that can travel from one place to another through empty space and can influence matter, but is not affected by gravity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Light Dependent Resistor (LDR)[/COLOR][/SIZE][/FONT][/B] LDRs are designed so that their resistance depends on the intensity(brightness) of light falling on them. [IMG]http://www.doctronics.co.uk/images/vdiv1.gif[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Light Emitting Diode [/COLOR][/SIZE][/FONT][/B] LEDs are simply diodes which emit light when connected correctly to a power supply. [IMG]http://www.physics.utoledo.edu/~lsa/_color/33_led-diagram.jpg[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Light-year [/COLOR][/SIZE][/FONT][/B] The light-year (ly) is a unit of distance which is useful in astronomy. It is the distance which light (or any other form of electromagnetic radiation) travels in one year,approximately 9.5 x 10^11 km. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Line spectrum[/COLOR][/SIZE][/FONT][/B] Narrow lines of color in an otherwise dark spectrum. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Lines of force[/COLOR][/SIZE][/FONT][/B] Lines drawn to make an electric field strength map, with each line originating on a positive charge and ending on a negative charge; each line represents a path on which a charge would experience a constant force and lines closer together means a stronger electric field. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Liquids [/COLOR][/SIZE][/FONT][/B] A phase of matter composed of molecules that have interactions stronger than those found in a gas but not strong enough to keep the molecules near the equilibrium positions of a solid, resulting in the characteristic definite volume but indefinite shape of a liquid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Liquid Crystal Display (LCD)[/COLOR][/SIZE][/FONT][/B] This is an output device. They run on almost no power since they don't produce their own light, but work by reflecting room or daylight. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Liter[/COLOR][/SIZE][/FONT][/B] A metric system unit of volume, usually used for liquids. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Logic Diagram [/COLOR][/SIZE][/FONT][/B] A simplified diagram of an electronic system, using rectangles to represent input and output devices along with the usual logic gate symbols for the AND, OR and NOT gate etc. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Logic Gate[/COLOR][/SIZE][/FONT][/B] Logic gates allow an electronic system to make decisions based on a number of inputs. For example an OR gate can be used to illuminate a warning light if engine temperature is too high or if it is over-revved. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Logic State [/COLOR][/SIZE][/FONT][/B] In a digital system, there are two logical states. One state is 'ON', 'HI' or 'logic 1' (all mean the same). The other is 'OFF', 'LOW', 'logic 0' (again all mean the same). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Longitudinal waves[/COLOR][/SIZE][/FONT][/B] The wave in which the particles of the medium oscillate along the direction of propagation of wave is called the longitudinal wave. Sound waves are longitudinal waves. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Long-sighted[/COLOR][/SIZE][/FONT][/B] A problem with the accommodation ability of an eye. Basically, the eye can focus on far away objects with no problem, but can't properly focus on nearby objects. There can be two causes of this. The first occurs in older people, where the aging eye lens becomes less flexible and so cannot adopt the highly curved shape needed to focus at short range. This condition is called presbyopia. The second cause is that retina is too near to the lens - so that the focal point falls behind the retina. This is called hypermetropia or hyperopia. Long-sightedness can be treated by wearing spectacles which are convex in shape and therefore help to focus the image properly by reducing the overall focal length of the glasses and eye. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Lorentz transformation[/COLOR][/SIZE][/FONT][/B] The transformation between frames in relative motion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Loudness[/COLOR][/SIZE][/FONT][/B] A subjective interpretation of a sound that is related to the energy of the vibrating source, related to the condition of the transmitting medium, and related to the distance involved. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Lubricant[/COLOR][/SIZE][/FONT][/B] A lubricant is a substance which reduces friction between two surfaces. Examples are oil, water, air, bananas, seaweed. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Luminosity[/COLOR][/SIZE][/FONT][/B] The total amount of energy radiated into space each second from the surface of a star. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Luminous[/COLOR][/SIZE][/FONT][/B] An object or objects that produce visible light; for example, the sun, stars, light bulbs, and burning materials are all luminous. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]M[/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnet[/COLOR][/SIZE][/FONT][/B] A magnet is a material or object that produces a magnetic field. A simple permanent magnet like a bar magnet has two poles, called 'North' and 'South'. Like poles repel and unlike poles attract. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnetic domain[/COLOR][/SIZE][/FONT][/B] Tiny physical regions in permanent magnets, approximately 0.01 to 1 mm, that have magnetically aligned atoms, giving the domain an overall polarity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnetic dipole[/COLOR][/SIZE][/FONT][/B] A dipole with opposing magnetic poles. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnetic field[/COLOR][/SIZE][/FONT][/B] A field of force, defined in terms of the torque exerted on a test dipole. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnetic poles[/COLOR][/SIZE][/FONT][/B] The ends, or sides, of a magnet about which the force of magnetic attraction seems to be concentrated. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnetic quantum number[/COLOR][/SIZE][/FONT][/B] The magnetic quantum number is the third of a set of quantum numbers (the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) which describe the unique quantum state of an electron and is designated by the letter m. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnetic reversal[/COLOR][/SIZE][/FONT][/B] The flipping of polarity of the earth's magnetic field as the north magnetic pole and the south magnetic pole exchange positions. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnification[/COLOR][/SIZE][/FONT][/B] The factor by which an image's linear size is increased (or decreased). Cf. angular magnification. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Magnitude[/COLOR][/SIZE][/FONT][/B] The size of a measurement of a vector and scalar quantities that consist of a number and unit only, no direction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mass defect[/COLOR][/SIZE][/FONT][/B] The difference between the sum of the masses of the individual nucleons forming a nucleus and the actual mass of that nucleus. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mass number[/COLOR][/SIZE][/FONT][/B] The sum of the number of protons and neutrons in a nucleus defines the mass number of an atom; used to identify isotopes; for example, Uranium 238. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mass [/COLOR][/SIZE][/FONT][/B] The quantity of matter contained in a body is called its mass. The SI unit of mass is kg. The mass of a body remains the same everywhere. It is a measure of inertia, which means a resistance to a change of motion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Matter[/COLOR][/SIZE][/FONT][/B] Objects that take up space and have mass are called matter. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mechanical energy[/COLOR][/SIZE][/FONT][/B] The form of energy associated with machines, objects in motion, and objects having potential energy that results from gravity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mechanical wave[/COLOR][/SIZE][/FONT][/B] The waves, which need a material medium for their propagation, are called mechanical waves. Mechanical waves are also called elastic waves. Sound waves, water waves are examples of mechanical waves. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Melting point[/COLOR][/SIZE][/FONT][/B] The temperature at which a phase change of solid to liquid takes place; the same temperature as the freezing point for a given substance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mercury (metal)[/COLOR][/SIZE][/FONT][/B] Mercury is a metal which is liquid at room temperature. It is often used in liquid in glass thermometers. It is a toxic substance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Metal[/COLOR][/SIZE][/FONT][/B] Matter having the physical properties of conductivity, malleability, ductility, and luster. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Meteorite[/COLOR][/SIZE][/FONT][/B] This is a lump of material which manages to reach Earth's surface, having only partially burned up on the way down. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Meteoroid [/COLOR][/SIZE][/FONT][/B] A solid object moving in interplanetary space, of a size considerably smaller than a asteroid and considerably larger than an atom or molecule. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Metre [/COLOR][/SIZE][/FONT][/B] The metre is the SI unit of length. The way it is defined means the speed of light is exactly 299,792,458 metres per second. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Microphone[/COLOR][/SIZE][/FONT][/B] A microphone is an input device in an electronic system. It converts sound energy into electrical energy. It is therefore a transducer. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Microwaves[/COLOR][/SIZE][/FONT][/B] Microwaves, along with light, UV, x-rays and gamma radiation form part of the electromagnetic spectrum. The wavelength of microwaves is longer than that of infra-red radiation, but shorter than that of radio waves. Microwaves are used commonly in mobile phones and in microwave ovens. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Millibar[/COLOR][/SIZE][/FONT][/B] A measure of atmospheric pressure equivalent to 1.000 dynes per cm ^2. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Milli rem[/COLOR][/SIZE][/FONT][/B] A unit of radiation exposure equal to one-thousandth of a REM. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Miniature Circuit Breaker (MCB)[/COLOR][/SIZE][/FONT][/B] Instead of using a fuse to protect an electrical flex, a miniature circuit breaker (MCB) can be used . MCBs are sometimes known as Earth Leakage Circuit Breakers (ELCBs) or Residual Current Devices (RCDs). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Miscible fluids[/COLOR][/SIZE][/FONT][/B] Fluids that can mix in any proportion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mixture [/COLOR][/SIZE][/FONT][/B] Matter made of unlike parts that have a variable composition and can be separated into their component parts by physical means. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mks system[/COLOR][/SIZE][/FONT][/B] Mks system system of units of measurement based on the metric system and having the meter of length, the kilogram of mass, and the second of time as its fundamental units. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Model[/COLOR][/SIZE][/FONT][/B] A mental or physical representation of something that cannot be observed directly that is usually used as an aid to understanding. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Moderator[/COLOR][/SIZE][/FONT][/B] In a nuclear fission reactor, the moderator slows fast neutrons down. Slower moving neutrons are more effective at keeping the chain reaction going by causing more uranium nuclei to break apart. Each fission event releases fast neutrons - the moderator is therefore required to slow them down. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Modulation[/COLOR][/SIZE][/FONT][/B] Modulation means change. In physics, this is usually used to describe changes made to the properties of a radio-wave or microwave carrier wave in order to carry information. There are two types of modulation - amplitude modulation and frequency modulation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Mole[/COLOR][/SIZE][/FONT][/B] An amount of a substance that contains Avogadro's number of atoms, ions, molecules, or any other chemical unit; a mole is thus 6.02 x 10^23 atoms, ions, or other chemical units. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Molecule[/COLOR][/SIZE][/FONT][/B] A group of atoms stuck together. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Momentum[/COLOR][/SIZE][/FONT][/B] Momentum is considered to be a measure of the quantity of motion in a body. The momentum of a body is defined as the product of its mass and velocity. Its SI units are kg m /s. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Morse Code [/COLOR][/SIZE][/FONT][/B] Morse Code is a versatile and simple method of transmitting information. It uses any method of telecommunication (such as flashing lights, tap keys and wires or radio transmissions) to send information coded as sequences of dots and dashes (e.g. short and long pulses of voltage or flashes of light). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Motor [/COLOR][/SIZE][/FONT][/B] Motors convert electrical energy into kinetic energy, along with some unwanted sound and heat energy. [IMG]http://hades.mech.northwestern.edu/wiki/images/thumb/c/cf/Motor_Commutators.jpg/400px-Motor_Commutators.jpg[/IMG] |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Natural frequency[/COLOR][/SIZE][/FONT][/B] The frequency of vibration of an elastic object that depends on the size, composition, and shape of the object. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Negative electric charge[/COLOR][/SIZE][/FONT][/B] One of the two types of electric charge; repels other negative charges and attracts positive charges. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Negative ion [/COLOR][/SIZE][/FONT][/B] Atom or particle that has a surplus, or imbalance, of electrons and, thus, a negative charge. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Net force[/COLOR][/SIZE][/FONT][/B] The resulting force after all vector forces have been added; if a net force is zero, all the forces have canceled each other and there is not an unbalanced force. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Neutron[/COLOR][/SIZE][/FONT][/B] Neutrons are sub-atomic particles. They are uncharged. They have a mass of mn = 1.675 x 10-27 kg. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton[/COLOR][/SIZE][/FONT][/B] Sir Isaac Newton, 1642-1727. Newton tried farming before going on to develop his three Laws of Motion. Newton also contributed to other branches of science and maths. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton[/COLOR][/SIZE][/FONT][/B] The newton (N) is the SI unit of force. An unbalanced force of 1 newton will cause a mass of 1 kg to accelerate at 1ms-2. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton Balance[/COLOR][/SIZE][/FONT][/B] This is a spring balance. It can be used to measure force, including weight forces. All forces are measured in newtons. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton's First Law[/COLOR][/SIZE][/FONT][/B] If the forces acting on an object are all balanced, then the object will not change in its motion. It will not speed up, slow down, change direction or shape. IF it is not moving, then it will stay stationary. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton's law of gravitation[/COLOR][/SIZE][/FONT][/B] The gravitational force of attraction acting between any two particles is directly proportional to the product of their masses, and inversely proportional to the square of the distance between them. The force of attraction acts along the line joining the two particles. Real bodies having spherical symmetry act as point masses with their mass assumed to be concentrated at their center of mass. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton's Second Law [/COLOR][/SIZE][/FONT][/B] If forces are not balanced on an object then it will either speed up, slow down or change direction - this means it will have to accelerate. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Newton's third law of motion [/COLOR][/SIZE][/FONT][/B] To every action there is an equal and opposite reaction. The action and reaction act on two different bodies simultaneously. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Noise[/COLOR][/SIZE][/FONT][/B] Sounds made up of groups of waves of random frequency and intensity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Non-Renewable Energy Sources [/COLOR][/SIZE][/FONT][/B] An energy resource that is not replaced or is replaced only very slowly by natural processes. Primary examples of non-renewable energy resources are the fossil fuels--oil, natural gas, and coal. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Noninertial frame[/COLOR][/SIZE][/FONT][/B] An accelerating frame of reference, in which Newton's first law is violated. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Non Uniform Acceleration [/COLOR][/SIZE][/FONT][/B] When the velocity of a body increases by unequal amounts in equal intervals of time, it is said to have non-uniform acceleration. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nonuniform circular motion[/COLOR][/SIZE][/FONT][/B] Circular motion in which the magnitude of the velocity vector changes. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Non Uniform Speed[/COLOR][/SIZE][/FONT][/B] When a body travels unequal distances in equal intervals of time then it is said to have non-uniform speed. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Non Uniform Velocity[/COLOR][/SIZE][/FONT][/B] When a body covers unequal distances in equal intervals of time in a particular direction, or when it covers equal distances in equal intervals but changes it's direction it is said to have non uniform velocity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Normalization[/COLOR][/SIZE][/FONT][/B] The property of probabilities that the sum of the probabilities of all possible outcomes must equal one. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Normal force[/COLOR][/SIZE][/FONT][/B] The force that keeps two objects from occupying the same space. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Normal Line [/COLOR][/SIZE][/FONT][/B] In optics and wave applications, the normal line is an imaginary line drawn at right angles to a surface. If the surface is curved, then the tangent to the surface must be drawn first, with the normal being drawn at right angles to the tangent. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Normal[/COLOR][/SIZE][/FONT][/B] A line perpendicular to the surface of a boundary. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]NOT gate (inverter)[/COLOR][/SIZE][/FONT][/B] The NOT gate or inverter is a digital logic gate that implements logical negation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nuclear Chain Reaction[/COLOR][/SIZE][/FONT][/B] A chain reaction refers to a process in which neutrons released in fission produce an additional fission in at least one further nucleus. This nucleus in turn produces neutrons, and the process repeats. The process may be controlled (nuclear power) or uncontrolled (nuclear weapons). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nuclear Energy[/COLOR][/SIZE][/FONT][/B] Nuclear energy is the energy contained within the nucleus of an atom. It can be released in nuclear fission or nuclear fusion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nuclear fission[/COLOR][/SIZE][/FONT][/B] Nuclear reaction of splitting a massive nucleus into more stable, less massive nuclei with an accompanying release of energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nuclear force[/COLOR][/SIZE][/FONT][/B] One of four fundamental forces, a strong force of attraction that operates over very short distances between subatomic particles; this force overcomes the electric repulsion of protons in a nucleus and binds the nucleus together. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nuclear fusion[/COLOR][/SIZE][/FONT][/B] Nuclear reaction of low mass nuclei fusing together to form more stable and more massive nuclei with an accompanying release of energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nuclear reactor [/COLOR][/SIZE][/FONT][/B] Steel vessel in which a controlled chain reaction of fissionable materials releases energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nucleons [/COLOR][/SIZE][/FONT][/B] Name used to refer to both the protons and neutrons in the nucleus of an atom. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Nucleus[/COLOR][/SIZE][/FONT][/B] The center of an atom. The nucleus contains tiny particles called protons and neutrons. Orbiting around the nucleus are electrons. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]O [/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Objective Lens [/COLOR][/SIZE][/FONT][/B] In a refracting telescope the objective lens is the large lens which collects the dim light from objects in the night sky. The purpose of the objective is to collect as much light as possible. It does not magnify the image. With a larger objective, the image will be brighter and fainter objects will become visible. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Oblique[/COLOR][/SIZE][/FONT][/B] Describes a force that acts at some other angle, one that is not a direct repulsion or attraction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Optical Fibres [/COLOR][/SIZE][/FONT][/B] Optically-pure glass fibre through which light can be reflected to transmit images or data from one end to the other. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Open Circuit[/COLOR][/SIZE][/FONT][/B] This is one of two types of circuit fault (the other being a short circuit). In an open circuit fault, there is a break in the circuit. This break will prevent any current from flowing. Open circuit faults register on an ohmmeter with an extremely high resistance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ohm (W)[/COLOR][/SIZE][/FONT][/B] The ohm is the SI unit of resistance. The resistance of an electrical component is one ohm (1 W) if, when a voltage of 1 V applied across it causes a current of 1 A to flow through it. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ohm's Law[/COLOR][/SIZE][/FONT][/B] Georg S. Ohm discovered that for a conductor at constant temperature, the current which flows through the conductor is proportional to the voltage across it. The constant of proportionality is called the resistance of the conductor. The law is usually written as: V = I R [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ohmic[/COLOR][/SIZE][/FONT][/B] Describes a substance in which the flow of current between two points is proportional to the voltage difference between them. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]OR Gate[/COLOR][/SIZE][/FONT][/B] An OR gate is a logical device. It usually takes two inputs (although more are possible) and produces only one output. The logic state of the output depends on the logic state of the inputs. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Operational definition[/COLOR][/SIZE][/FONT][/B] A definition that states what operations should be carried out to measure the thing being defined. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Orbital [/COLOR][/SIZE][/FONT][/B] The region of space around the nucleus of an atom where an electron is likely to be found. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Origin [/COLOR][/SIZE][/FONT][/B] The only point on a graph where both the x and y variables have a value of zero at the same time. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Oscilloscope[/COLOR][/SIZE][/FONT][/B] Electronic instrument for viewing and measuring electrical and electronic signals. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Oscillatory motion[/COLOR][/SIZE][/FONT][/B] The to and fro motion of a body about its mean position is called oscillatory motion. Oscillatory motion is also called vibratory motion. Oscillatory motion is periodic in nature. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]P[/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Parabola[/COLOR][/FONT][/SIZE][/B] The mathematical curve whose graph has y proportional to x2. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Parallel Beam [/COLOR][/FONT][/SIZE][/B] A parallel beam is one which does not diverge or converge - its width stays the same as the wave (which could be light or microwaves for example) travels out from its source. Parallel beams are produced using curved (parabolic) reflector dishes. Parallel light beams can also be produced using convex lenses (e.g. in binoculars or telescopes). Parallel beams can be used to send waves over much greater distances than would otherwise be possible. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Parallel Circuit[/COLOR][/FONT][/SIZE][/B] In a parallel circuit, each component is connected directly across the terminals of the power supply. Therefore, the voltage across any component is the same as the voltage across the power supply terminals. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Pauli exclusion principle[/COLOR][/FONT][/SIZE][/B] No two electrons in an atom can have the same four quantum numbers; thus, a maximum of two electrons can occupy a given orbital. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Peak [/COLOR][/FONT][/SIZE][/B] This refers to waves. The peak of a wave (also called the crest) is simply the part of the wave with the greatest amplitude. [IMG]http://www.mitedu.freeserve.co.uk/Design/dcpsu/peak_value.gif[/IMG] [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Peak Voltage [/COLOR][/FONT][/SIZE][/B] This is the maximum voltage reached by an a.c. source in each cycle. It is very similar to the peak or crest of a wave. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Period[/COLOR][/FONT][/SIZE][/B] The time required for one cycle of a periodic motion (q.v.). [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Periodic motion[/COLOR][/FONT][/SIZE][/B] Motion that repeats itself over and over. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Periodic wave[/COLOR][/FONT][/SIZE][/B] A wave in which the particles of the medium oscillate continuously about their mean positions regularly at fixed intervals of time is called a periodic wave. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Permeability[/COLOR][/FONT][/SIZE][/B] The ability to transmit fluids through openings, small passageways, or gaps. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Persistence of Vision[/COLOR][/FONT][/SIZE][/B] This is the effect which allows the human brain to be fooled into thinking that the 25 frames per second of TV is actually continuous motion. The retina retains each image for a fraction of a second and so provided that the changes between the frames are small enough, smooth motion will be seen. (The phosphor dots which make up the screen also continue to emit light for a short time after the electron beam has passed - this effect also helps to give the impression of a smooth motion). [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Photographic_film[/COLOR][/FONT][/SIZE][/B] Photographic film can be used to detect visible light, x-rays, or alpha, beta and gamma radiation. These radiations will blacken film due to a chemical reaction. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Phase change[/COLOR][/FONT][/SIZE][/B] The action of a substance changing from one state of matter to another; a phase change always absorbs or releases internal potential energy that is not associated with a temperature change. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Phase [/COLOR][/FONT][/SIZE][/B] The particles in a wave, which are in the same state of vibration, i.e. the same position and the same direction of motion are said to be in the same phase. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Phases of matter[/COLOR][/FONT][/SIZE][/B] The different physical forms that matter can take as a result of different molecular arrangements, resulting in characteristics of the common phases of a solid, liquid, or gas. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Photon[/COLOR][/FONT][/SIZE][/B] A particle of light. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Photoelectric effect[/COLOR][/FONT][/SIZE][/B] The ejection, by a photon, of an electron from the surface of an object. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Physical change[/COLOR][/FONT][/SIZE][/B] A change of the state of a substance but not the identity of the substance pitch the frequency of a sound wave. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Planck's constant[/COLOR][/FONT][/SIZE][/B] Proportionality constant in the relationship between the energy of vibrating molecules and their frequency of vibration; a value of 6.63 x 10^-34 joule-sec. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Plasma[/COLOR][/FONT][/SIZE][/B] A phase of matter; a very hot gas consisting of electrons and atoms that have been stripped of their electrons because of high kinetic energies. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Plastic strain [/COLOR][/FONT][/SIZE][/B] An adjustment to stress in which materials become molded or bent out of shape under stress and do not return to their original shape after the stress is released. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Polarized [/COLOR][/FONT][/SIZE][/B] Light whose constituent transverse waves are all vibrating in the same plane; also known as plane polarized light. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Polaroid[/COLOR][/FONT][/SIZE][/B] A film that transmits only polarized light. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Positive electric charge[/COLOR][/FONT][/SIZE][/B] One of the two types of electric charge; repels other positive charges and attracts negative charges. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Positive ion[/COLOR][/FONT][/SIZE][/B] Atom or particle that has a net positive charge due to an electron or electrons being torn away. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Potential Divider (potentiometer) [/COLOR][/FONT][/SIZE][/B] A variable resistor, when used with all three of its terminals, it is called a potentiometer or potential divider. This arrangement is for controlling voltage. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Potential Energy[/COLOR][/FONT][/SIZE][/B] Potential energy means stored energy. Some examples are chemical, elastic, nuclear and gravitational - all forms of potential energy. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Power[/COLOR][/FONT][/SIZE][/B] Power is the rate of transfer of energy. The SI unit of power is the watt (W). One watt is the same as one joule per second. The formula which relates power (P), energy (E) and time (t) is: E = P x t In electrical applications, there are other equations for power, which involve current, voltage and resistance. They are: P = I V P = I2R P = V2 / R [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Power (of a lens)[/COLOR][/FONT][/SIZE][/B] Lens power describes the curvature of a lens. High power lenses have a short focal length and are highly curved. A positive lens power indicates a convex lens and negative power indicates a concave lens. Lens power, P, is measured in Dioptres (D) and is related to the focal length, f, in metres through the formula: P = 1 / f [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Power Gain [/COLOR][/FONT][/SIZE][/B] Power gain has no units of its own. It expresses how many times more power the output signal from a process has compared to its input power. A closely related concept is that of voltage gain. Power Gain = Output Power / Input Power. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Presbyopia (presbyopic eye) [/COLOR][/FONT][/SIZE][/B] A form of farsightedness occurring after middle age, caused by a diminished elasticity of the crystalline lens. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Pressure [/COLOR][/FONT][/SIZE][/B] Defined as force per unit area; for example, pounds per square inch (lb/in^2). [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Primary Colours [/COLOR][/FONT][/SIZE][/B] There are three primary colours (of light): red, green and blue. Any two of these colours can be mixed to give a secondary colour as follows: Red + Green = Yellow Red + Blue = Magenta (pink) Green + Blue = Cyan (Turquoise) If all three colours are mixed together, white light can be obtained. These are the primary and secondary colours of light. The primary and secondary colours of pigment (paint) are not the same. [IMG]http://rst.gsfc.nasa.gov/Intro/Fig10_10.jpg[/IMG] [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Primary coil[/COLOR][/FONT][/SIZE][/B] Part of a transformer; a coil of wire that is connected to a source of alternating current. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Primary Mirror [/COLOR][/FONT][/SIZE][/B] In a reflecting telescope, the primary mirror collects the light from the objects under study in the night sky. Reflectors can be made much bigger than the objective lenses of a refracting telescope. They are also easier to make, since their is only one optical surface to prepare. The primary mirror itself is usually made from glass, with an aluminium coating on its forward face. The mirror is made as large as possible for the same reasons as for the objective lens of a refractor. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Principle of calorimetry[/COLOR][/FONT][/SIZE][/B] If no heat is lost to the surroundings and there is no change of state also. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Principle quantum number [/COLOR][/FONT][/SIZE][/B] From quantum mechanics model of the atom, one of four descriptions of the energy state of an electron wave; this quantum number describes the main energy level of an electron in terms of its most probable distance from the nucleus. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Principle of Reversibility[/COLOR][/FONT][/SIZE][/B] This applies to light rays passing through any system of mirrors or lenses. Basically, it means if a ray of light follows a path when going, say, from left to right, then another ray of light going from right to left will follow the same path in reverse. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Probability[/COLOR][/FONT][/SIZE][/B] The likelihood that something will happen, expressed as a number between zero and one. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Probability distribution[/COLOR][/FONT][/SIZE][/B] A curve that specifies the probabilities of various random values of a variable; areas under the curve correspond to probabilities. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Projectile[/COLOR][/FONT][/SIZE][/B] An object thrown into space either horizontally or at an acute angle and under the action of gravity is called a projectile. The path followed by a projectile is called its trajectory. The horizontal distance traveled by a projectile is called its range. The time taken by a projectile from the moment it is thrown until it touches the ground is called its time of flight. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Proof[/COLOR][/FONT][/SIZE][/B] A measure of ethanol concentration of an alcoholic beverage; proof is double the concentration by volume; for example, 50 percent by volume is 100 proof. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Properties[/COLOR][/FONT][/SIZE][/B] Qualities or attributes that, taken together, are usually unique to an object; for example, color, texture, and size. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Proportionality constant[/COLOR][/FONT][/SIZE][/B] A constant applied to a proportionality statement that transforms the statement into an equation. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Proton[/COLOR][/FONT][/SIZE][/B] Protons are sub-atomic particles. They carry a positive electrical charge (qp = +1.602 x 10-19 C). They have a mass of mp = 1.673 x 10-27 kg. [B][SIZE="4"][FONT="Comic Sans MS"][COLOR="Blue"]Pulse[/COLOR][/FONT][/SIZE][/B] A wave of short duration confined to a small portion of the medium at any given time is called a pulse. A pulse is also called a wave pulse. |
[B][CENTER][FONT=Comic Sans MS][SIZE=6][COLOR=blue]Q [/COLOR][/SIZE][/FONT][/CENTER]
[/B] [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Quanta[/COLOR][/SIZE][/FONT][/B] Fixed amounts; usually referring to fixed amounts of energy absorbed or emitted by matter. " [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Quantum number[/COLOR][/SIZE][/FONT][/B] A numerical label used to classify a quantum state. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Quantum mechanics[/COLOR][/SIZE][/FONT][/B] Model of the atom based on the wave nature of subatomic particles, the mechanics of electron waves; also called wave mechanics. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Quality factor[/COLOR][/SIZE][/FONT][/B] The number of oscillations required for a system's energy to fall off by a factor of 535 due to damping. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Quantized[/COLOR][/SIZE][/FONT][/B] Describes quantity such as money or electrical charge that can only exist in certain amounts. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Quasar[/COLOR][/SIZE][/FONT][/B] Quasar means 'quasi-stellar radar source'. These are objects which look like stars but are not. (They are only visible in big telescopes, because of their great distance from us. A typical quasar differs most noticeably from a star because it gives off the same intensity of light as would one million suns). [B][CENTER][FONT=Comic Sans MS][SIZE=6][COLOR=blue]R[/COLOR][/SIZE][/FONT][/CENTER] [/B] [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rad [/COLOR][/SIZE][/FONT][/B] A measure of radiation received by a material (radiation absorbed dose). [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radar Gun[/COLOR][/SIZE][/FONT][/B] A hand-held device used by police to measure the speed of passing cars. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radial[/COLOR][/SIZE][/FONT][/B] Parallel to the radius of a circle; the in-out direction. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radiant energy[/COLOR][/SIZE][/FONT][/B] The form of energy that can travel through space; for example, visible light and other parts of the electromagnetic spectrum. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radiation[/COLOR][/SIZE][/FONT][/B] The word 'radiation' can refer to electromagnetic radiation (including gamma radiation) or to alpha and beta particles released from radioactive decay. Radiation can cause ionisation of neutral atoms, by knocking away electrons. This can damage or kill cells. In this way, radiation can cause cancer and be used to treat cancer. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radiation (heat)[/COLOR][/SIZE][/FONT][/B] Heat radiation is a part of the electromagnetic spectrum, conventionally called 'infra-red'. Heat can be transferred from a hot object to a cold one by radiation, convection or conduction. Transfer by radiation is possible in a vacuum (or in presence of matter). [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radioactive decay constant[/COLOR][/SIZE][/FONT][/B] A specific constant for a particular isotope that is the ratio of the rate of nuclear disintegration per unit of time to the total number of radioactive nuclei. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radioactive decay series [/COLOR][/SIZE][/FONT][/B] Series of decay reactions that begins with one radioactive nucleus that decays to a second nucleus that decays to a third nucleus and so on until a stable nucleus is reached. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radioactive decay [/COLOR][/SIZE][/FONT][/B] The natural spontaneous disintegration or decomposition of a nucleus. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radioactivity [/COLOR][/SIZE][/FONT][/B] Spontaneous emission of particles or energy from an atomic nucleus as it disintegrates. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radio [/COLOR][/SIZE][/FONT][/B] A radio is an electronic system which allows a listener to hear programmers sent from a transmitter. The main components of a radio (in order) are: the aerial, tuner, decoder, amplifier and loudspeaker. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radioactive [/COLOR][/SIZE][/FONT][/B] A material is said to be radioactive if it emits radiation. Radioactive materials have unstable nuclei which have a tendency to decay. It is when a decay occurs that radiation is released from the nucleus. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radiometric Dating[/COLOR][/SIZE][/FONT][/B] This is the name given to the general technique of using half-life to find out the age of samples of rock, fossil or material which is organic in nature. Carbon dating is used to date organic material up to about 30 000 years. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radio Telescope [/COLOR][/SIZE][/FONT][/B] Astronomers use radio telescopes to help build up a picture of the Universe. Since radio waves can penetrate Earth's atmosphere, we can detect them by building large antennae or dishes. The radio part of the spectrum provides an alternative and complimentary view of the Universe - importantly radio waves convey information about much lower energy events than visible light does, much of what a radio telescope 'sees' will be not appear in visible light images. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Radio Transmitter [/COLOR][/SIZE][/FONT][/B] A source of radio waves. Radio transmitters are usually large vertical conducting masts which emit radio waves. Moving electrons in the metal of the mast radiate the radio waves. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rem [/COLOR][/SIZE][/FONT][/B] A unit for measuring a person's exposure to radioactivity. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Red shift [/COLOR][/SIZE][/FONT][/B] This refers to the fact that the spectrum of distant galaxies is shifted towards the long wavelength 'red' end of the electromagnetic spectrum. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rarefaction[/COLOR][/SIZE][/FONT][/B] A part of a longitudinal wave in which the density of the particles of the medium is less than the normal density is called a rarefaction. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Real image[/COLOR][/SIZE][/FONT][/B] An image generated by a lens or mirror that can be projected onto a screen. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rectilinear Motion[/COLOR][/SIZE][/FONT][/B] The motion of a body in a straight line is called rectilinear motion. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Reed Relay[/COLOR][/SIZE][/FONT][/B] Relays can be used for remote control of electrical circuits in dangerous places. For example, a circuit within a nuclear reactor can be switched on or off with a reed relay. In general, relays can be used to switch high current circuits using low current circuits. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Reed Switch[/COLOR][/SIZE][/FONT][/B] A simple switch, controlled by a magnet. The reed switch can be designed either to make or break contact when a magnetic field is present. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Reflected ray[/COLOR][/SIZE][/FONT][/B] A line representing direction of motion of light reflected from a boundary. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Reflection [/COLOR][/SIZE][/FONT][/B] The change when light, sound, or other waves bounce backwards off a boundary. All waves can be reflected from an obstacle - for example, water waves can reflect off a harbour wall and light waves can reflect off a mirror. The law of reflection is very simple: The angle of incidence is equal to the angle of reflection. [IMG]http://laser.physics.sunysb.edu/~amy/wise2000/websites/Mirror348.jpg[/IMG] [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Refraction [/COLOR][/SIZE][/FONT][/B] All waves can be refracted. Refraction means bending. Light rays refract when they pass through a medium of different density (e.g. when light travels from air into glass). When light passes into a region of increased density (e.g. air to glass) it bends towards the normal. When light passes into a region of reduced density, it bends away from the normal. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Relative humidity[/COLOR][/SIZE][/FONT][/B] The percentage of the amount of water vapor actually present in a certain volume of the air to the amount of water vapor needed to saturate it is called the relative humidity of the air. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Renewable Energy Sources[/COLOR][/SIZE][/FONT][/B] Solar, wind, geothermal, tidal and wave power plants are examples of renewable energy resources. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Repulsive[/COLOR][/SIZE][/FONT][/B] Describes a force that tends to push the two participating objects apart. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Resistance[/COLOR][/SIZE][/FONT][/B] The ratio of the voltage difference to the current in an object made of an ohmic substance.The SI unit of resistance is the ohm (W). [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Resistor[/COLOR][/SIZE][/FONT][/B] A resistor is an electronic component which opposes the flow of current. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Resonance[/COLOR][/SIZE][/FONT][/B] The tendency of a vibrating system to respond most strongly to a driving force whose frequency is close to its own natural frequency of vibration. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Restoring force[/COLOR][/SIZE][/FONT][/B] The force which tends to bring an oscillating body towards its mean position whenever it is displaced from the mean position is called the restoring force. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rest mass[/COLOR][/SIZE][/FONT][/B] The rest mass of an object is the inertial mass that an object has when it is at rest. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Resultant Force[/COLOR][/SIZE][/FONT][/B] A single force, which acts on a body to produce the same effect in it as, done by all other forces collectively, is called the resultant force. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Retardation[/COLOR][/SIZE][/FONT][/B] Negative acceleration is called retardation. In retardation the velocity of a body decreases with time. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Reverberation[/COLOR][/SIZE][/FONT][/B] Apparent increase in volume caused by reflections, usually arriving within 0.1 second after the original sound. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rheostat[/COLOR][/SIZE][/FONT][/B] A variable resistor, when used with just two of its terminals, it is called a rheostat. This arrangement is for controlling current. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Ring Circuit[/COLOR][/SIZE][/FONT][/B] This is a special type of parallel circuit, used in household wiring. The advantage of the ring circuit is that thinner, cheaper cable can be used. This is because there are two separate paths to any socket. Therefore, if each cable is capable of carrying up to 18 A, then the maximum current the ring can draw from the consumer unit is 36 A. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]R.M.S. Voltage[/COLOR][/SIZE][/FONT][/B] This is a kind of average voltage of an a.c. source (averaged over a complete cycle). It is the effective voltage delivered by the source and can be used in power calculations. [B][FONT=Comic Sans MS][SIZE=4][COLOR=blue]Rotor Coil[/COLOR][/SIZE][/FONT][/B] In an a.c. generator, the rotor coil is a rotating electromagnet, with a d.c. power supply. It replaces the permanent rotating magnets of a dynamo. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Saturated air[/COLOR][/SIZE][/FONT][/B] Air in which equilibrium exists between evaporation and condensation; the relative humidity is 100 percent. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Saturated solution[/COLOR][/SIZE][/FONT][/B] The apparent limit to dissolving a given solid in a specified amount of water at a given temperature; a state of equilibrium that exists between dissolving solute and solute coming out of solution. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Scalar[/COLOR][/SIZE][/FONT][/B] A quantity that has no direction in space, only an amount. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Scientific law[/COLOR][/SIZE][/FONT][/B] A relationship between quantities, usually described by an equation in the physical sciences; is more important and describes a wider range of phenomena than a scientific principle. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Scientific principle[/COLOR][/SIZE][/FONT][/B] A relationship between quantities concerned with a specific, or narrow range of observations and behavior. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Scintillation Counter[/COLOR][/SIZE][/FONT][/B] These devices detect gamma rays and form part of the gamma cameras used in radioactive tracer examinations. Scintillations are flashes of light given out by fluorescent materials (e.g zinc sulphide). When radiation is absorbed by zinc sulphide, it causes the zinc sulphide to produce a small burst of light. These can be electronically counted. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Second law of motion[/COLOR][/SIZE][/FONT][/B] The acceleration of an object is directly proportional to the net force acting on that object and inversely proportional to the mass of the object. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Second[/COLOR][/SIZE][/FONT][/B] The second is the SI unit of time. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Secondary coil[/COLOR][/SIZE][/FONT][/B] Part of a transformer, a coil of wire in which the voltage of the original alternating current in the primary coil is stepped up or down by way of electromagnetic induction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Second's Pendulum[/COLOR][/SIZE][/FONT][/B] A simple pendulum whose time period on the surface of earth is 2 seconds is called the second''s pendulum. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Semiconductors[/COLOR][/SIZE][/FONT][/B] Elements that have properties between those of a metal and those of a nonmetal sometimes conducting an electric current and sometimes acting like an electrical insulator depending on the conditions and their purity; also called metalloid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Series Circuit[/COLOR][/SIZE][/FONT][/B] In a series circuit, each component is connected to the other to form a 'chain' between the terminals of the power supply. The rules for current, voltage and resistance in a series circuit are as follows: Vsupply = V1 + V2 + V3 + ... Isupply = I1 = I2 = I3 = ... Rtotal = R1 + R2 + R3 + ... The mnemonic VISA may help to remember the rules for voltage and current in series and parallel circuits: VISA: Voltages In Series Add [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Shear stress[/COLOR][/SIZE][/FONT][/B] Produced when two plates slide past one another or by one plate sliding past another plate that is not moving. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Short Circuit[/COLOR][/SIZE][/FONT][/B] This is one of two types of circuit fault (the other being an open circuit). A short circuit fault is often caused by wires touching, allowing current to bypass a component in the circuit. Short circuit faults register on an ohmmeter with almost zero resistance. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Short-sighted[/COLOR][/SIZE][/FONT][/B] This refers to a problem with the accommodation ability of an eye. Basically, the eye can focus on near-by objects with no problem, but can't properly focus on far-away objects. This is called myopia. This is because the retina is too far from the lens - so that the focal point falls short of the retina. Short-sightedness can be treated by wearing spectacles which are concave in shape and therefore help to focus the image properly by extending the overall focal length of the glasses and eye. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Sievert (Sv)[/COLOR][/SIZE][/FONT][/B] The sievert is the SI unit of dose equivalent. Since 1 Sv is a massive dose of radiation, units of microsieverts are often used instead. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Significant figures[/COLOR][/SIZE][/FONT][/B] Digits that contribute to the accuracy of a measurement. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Simple harmonic motion [/COLOR][/SIZE][/FONT][/B] The vibratory motion that occurs when there is a restoring force opposite to and proportional to a displacement. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Simple Pendulum[/COLOR][/SIZE][/FONT][/B] A heavy point mass (actually a small metallic ball), suspended by a light inextensible string from a frictionless rigid support is called a simple pendulum. A simple pendulum is a simple machine based on the effect of gravity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Sink[/COLOR][/SIZE][/FONT][/B] A point at which field vectors converge. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]SI Units[/COLOR][/SIZE][/FONT][/B] SI stands for System International. This is the standard system of units used worldwide and includes the metre, the second, the kilogram, the ampere, the kelvin, and the coulomb. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Solenoid[/COLOR][/SIZE][/FONT][/B] A solenoid is a coil of wire with an electrical current flowing through it. An iron core, inserted into the coil, has the effect of increasing the strength of the magnetic field produced. An increased current or a greater number of turns on the coil will also increase the strength of the magnetic field. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Solar Cell[/COLOR][/SIZE][/FONT][/B] A solar cell is a photovoltaic semiconductor material which converts light energy into electrical energy. Solar cells are transducers. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Solids [/COLOR][/SIZE][/FONT][/B] A phase of matter with molecules that remain close to fixed equilibrium positions due to strong interactions between the molecules, resulting in the characteristic definite shape and definite volume of a solid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Sonic boom[/COLOR][/SIZE][/FONT][/B] Sound waves that pile up into a shock wave when a source is traveling at or faster than the speed of sound. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Sound [/COLOR][/SIZE][/FONT][/B] A longitudinal wave which travels through a medium, usually air. Sound also travels through liquids (e.g. water) and solids (e.g. steel). The volume (loudness) of sound is measured using the decibel (dB) scale. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Source[/COLOR][/SIZE][/FONT][/B] A point from which field vectors diverge; often used more inclusively to refer to points of either convergence or divergence. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Specific Heat Capacity[/COLOR][/SIZE][/FONT][/B] The energy required to increase the temperature of 1kg of a material by 1 degree Celsius. This is also the energy released during cooling. Water has a high specific heat capacity at 4200 Jkg-1 oC-1. Metals have much lower heat capacities. Physically, this is why metals heat up and cool down more rapidly than water - less energy is required to bring about a given change in temperature. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Specific Latent Heat of Fusion [/COLOR][/SIZE][/FONT][/B] This is the latent heat per kilogram of material required to change its phase from solid to liquid (i.e. heat energy required to melt 1 kg of material). It is also the heat energy released (in joules) if 1 kg of material 'freezes' from liquid to solid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Specific Latent Heat of Vapourisation [/COLOR][/SIZE][/FONT][/B] This is the latent heat per kilogram of material required to change the material's phase from liquid to gas (i.e. heat energy required to boil or vapourise 1 kg of material). It is also the heat energy released (in joules) if 1 kg of material condenses from solid to liquid. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Spectroscope[/COLOR][/SIZE][/FONT][/B] A device using the diffraction of light to split the visible spectrum up into the rainbow of colours. The spectroscope is used in astronomy to study the spectra of light from the stars. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Spectrum [/COLOR][/SIZE][/FONT][/B] The electromagnetic spectrum includes all types of electromagnetic radiation(EMR). All types of EMR travel at the same speed: the speed of light, which is 3 x 108 ms-1. Starting with the lowest frequency and longest wavelength radiation, the spectrum consists of: [LIST][*]Radiowaves [*]Microwaves[*]Infrared Radiation [*]Visible Radiation (red, orange, yellow, green , blue, indigo, violet) [*]Ultraviolet Radiation [*]X-Ray Radiation [*]Cosmic Radiation[/LIST] The visible spectrum includes red, orange, yellow, green , blue, indigo, violet. Red light has a wavelength of approximately 700 nm and violet light's wavelength is roughly 400 nm. All other colours have a wavelength between these two limits. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Speed [/COLOR][/SIZE][/FONT][/B] The distance traveled by a body in one unit of time is called its speed. The SI unit of speed is the metre per second. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Speed Time Graph[/COLOR][/SIZE][/FONT][/B] This is a graph with time plotted along the horizontal axis, and with speed up the vertical axis. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Specular reflection[/COLOR][/SIZE][/FONT][/B] Reflection from a smooth surface, in which the light ray leaves at the same angle at which it came in. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Spin quantum number[/COLOR][/SIZE][/FONT][/B] The quantum number describes the spin orientation of an electron relative to an external magnetic field. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Spin[/COLOR][/SIZE][/FONT][/B] The built-in angular momentum possessed by a particle even when at rest. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Stable equilibrium[/COLOR][/SIZE][/FONT][/B] One in which a force always acts to bring the object back to a certain point. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Standing waves[/COLOR][/SIZE][/FONT][/B] Condition where two waves of equal frequency traveling in opposite directions meet and form stationary regions of maximum displacement due to constructive interference and stationary regions of zero displacement due to destructive interference. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]State of Motion[/COLOR][/SIZE][/FONT][/B] When a body changes it's position with respect to a fixed point in it's surroundings then it is said to be in a state of motion. The states of rest and motion are relative to the frame of reference. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]State of Rest [/COLOR][/SIZE][/FONT][/B] When a body does not change its position with respect to a fixed point in it's surrounding, then it is said to be in a state of rest. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Static friction[/COLOR][/SIZE][/FONT][/B] A friction force between surfaces that are not slipping past each other. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Stator Coil[/COLOR][/SIZE][/FONT][/B] In a dynamo, the stator coil is the the fixed coil which has an electric current (a.c.) induced in it by the motion of the nearby rotor (permanent magnet). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Steady state[/COLOR][/SIZE][/FONT][/B] The behavior of a vibrating system after it has had plenty of time to settle into a steady response to a driving force. In the steady state, the same amount of energy is pumped into the system during each cycle as is lost to damping during the same period. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Steam-point[/COLOR][/SIZE][/FONT][/B] It is the temperature of steam over pure boiling water under 1 atm pressure. The steam point is taken as the upper fixed point (100 deg C or 212 deg F) for temperature scales. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Streamlined [/COLOR][/SIZE][/FONT][/B] Streamlined objects are designed to reduce fluid drag forces. All rough or angular edges are removed, leaving only smooth curved surfaces. Fish, dolphins, falcons, air interceptors and racing cars are good examples of streamlined objects. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Strong nuclear force[/COLOR][/SIZE][/FONT][/B] The force that holds nuclei together against electrical repulsion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Superconductors[/COLOR][/SIZE][/FONT][/B] Some materials in which, under certain conditions, the electrical resistance approaches zero. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Super-cooled [/COLOR][/SIZE][/FONT][/B] Water in the liquid phase when the temperature is below the freezing point. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Supersaturated [/COLOR][/SIZE][/FONT][/B] Containing more than the normal saturation amount of a solute at a given temperature. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]System International[/COLOR][/SIZE][/FONT][/B] Fancy name for the metric system. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Tangential [/COLOR][/SIZE][/FONT][/B] Tangent to a curve. In circular motion, used to mean tangent to the circle, perpendicular to the radial direction. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Temperature[/COLOR][/SIZE][/FONT][/B] A measure of the energy in a substance. The more heat energy in the substance, the higher the temperature. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Tensional stress [/COLOR][/SIZE][/FONT][/B] The opposite of compressional stress; occurs when one part of a plate moves away from another part that does not move. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermal Capacity[/COLOR][/SIZE][/FONT][/B] The quantity of heat required to raise the temperature of the whole body by one degree (1K or 1deg C) is called its thermal capacity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermal energy[/COLOR][/SIZE][/FONT][/B] Thermal energy is used to mean the total amount of energy possessed by an object. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermal Equilibrium [/COLOR][/SIZE][/FONT][/B] When the two bodies in contact are at the same temperature and there is no flow of heat between them, these are said to be in thermal equilibrium. The common temperature of the bodies in thermal equilibrium is called the equilibrium temperature. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermal Expansion [/COLOR][/SIZE][/FONT][/B] The increase in the size of an object on heating is called thermal expansion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermistor [/COLOR][/SIZE][/FONT][/B] A thermistor is a thermally sensitive resistor whose primary function is to exhibit a change in electrical resistance with a change in body temperature. When subjected to low temperatures, the resistance of a thermistor is high. When subjected to a high temperature, the resistance of a thermistor is low. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermocouple[/COLOR][/SIZE][/FONT][/B] When two different metals are joined together, they will convert heat energy into electrical energy. This is the basis of the thermocouple. Thermocouples are transducers. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Thermometer[/COLOR][/SIZE][/FONT][/B] It is a device used for numerical measurement of temperature. The commonly used thermometer is mercury thermometer. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Third law of motion[/COLOR][/SIZE][/FONT][/B] Whenever two objects interact, the force exerted on one object is equal in size and opposite in direction to the force exerted on the other object; forces always occur in matched pairs that are equal and opposite. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Time Period (of a wave) [/COLOR][/SIZE][/FONT][/B] The time taken by a wave to travel through a distance equal to its wavelength is called its time period. It is denoted by T. Time period of a wave=1/frequency of the wave. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Time Period (of an oscillation) [/COLOR][/SIZE][/FONT][/B] The time taken to complete one oscillation is called the time period of an oscillation. The time period of a pendulum does not depend upon the mass of the bob and amplitude of oscillation. The time period of a pendulum is directly proportional to the square root of the length and inversely proportional to the square root of the acceleration due to gravity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Torque [/COLOR][/SIZE][/FONT][/B] The rate of change of angular momentum; a numerical measure of a force's ability to twist on an object. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Total Internal Reflection (TIR) [/COLOR][/SIZE][/FONT][/B] Total internal reflection occurs when light, instead of being refracted at a boundary between media of different densities, the light is totally reflected off the inside surface. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Tracer[/COLOR][/SIZE][/FONT][/B] Radioactive tracers are injected into a patient to examine the function of organs and blood supplies within the body. Technetium is often used as it emits gamma radiation which can be detected outside the patient's body. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Transducer[/COLOR][/SIZE][/FONT][/B] Any device which converts one form of energy into another. For example, a microphone, a TV, a car or a solar cell. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Transistor[/COLOR][/SIZE][/FONT][/B] A semiconductor device which can be used as an electronic switch. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Transformation [/COLOR][/SIZE][/FONT][/B] The mathematical relationship between the variables such as x and t, as observed in different frames of reference. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Transformer[/COLOR][/SIZE][/FONT][/B] A device used to increase or decrease electricity’s voltage and current, which consists of two separate coils. Transformers only work with a.c. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Transverse waves[/COLOR][/SIZE][/FONT][/B] A wave in which the particles of the medium oscillate in a direction perpendicular of the direction of propagation of wave is called the transverse wave. Water waves, light waves and radio waves are examples of transverse waves. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Trough [/COLOR][/SIZE][/FONT][/B] This refers to waves. The trough of a wave is simply the part of the wave with the least (most negative) amplitude. [IMG]http://www.hobbyprojects.com/general_theory/images/ampmod2.gif[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Truth Table[/COLOR][/SIZE][/FONT][/B] A table showing the output logic states of a logic gate or logic system for all given combinations of input logic states. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Tuner (Radio or TV) [/COLOR][/SIZE][/FONT][/B] The tuner in a radio or TV allows the user to select one channel from the many channels which arrive at the aerial. The output signal from the tuner section is then passed to the decoder. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Two-stage Rocket[/COLOR][/SIZE][/FONT][/B] Essentially, two rockets one on top of the other. The top rocket will not ignite until the first rocket is finished and jettisoned. The advantage over a big single stage rocket is that all the dead weight of the empty first stage can be cut away and left to fall back to Earth. This can greatly reduce the total mass of fuel required to reach orbit. |
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[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ultrasonic [/COLOR][/SIZE][/FONT][/B] Sound waves too high in frequency to be heard by the human ear; frequencies above 20,000Hz. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Ultraviolet[/COLOR][/SIZE][/FONT][/B] Ultraviolet (UV) radiation is invisible. It is a form of electromagnetic radiation, with a wavelength just shorter than that of visible violet light. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Unbalanced forces[/COLOR][/SIZE][/FONT][/B] When a number of forces act on a body and the resultant force is not zero, then the forces are said to be unbalanced. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Uniform Acceleration[/COLOR][/SIZE][/FONT][/B] When the velocity of a body increases by equal amounts in equal intervals of time it is said to have uniform acceleration. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Uniform circular motion[/COLOR][/SIZE][/FONT][/B] Circular motion in which the magnitude of the velocity vector remains constant. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Uniform Speed[/COLOR][/SIZE][/FONT][/B] When a body travels equal distances in equal intervals of time then it is said to have uniform speed. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Uniform Velocity[/COLOR][/SIZE][/FONT][/B] When a body travels along a straight line in particular direction and covers equal distances in equal intervals of time it is said to have uniform velocity. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Universal law of gravitation[/COLOR][/SIZE][/FONT][/B] Every object in the universe is attracted to every other object with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between the centers of the two masses. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Unpolarized light[/COLOR][/SIZE][/FONT][/B] Light consisting of transverse waves vibrating in all conceivable random directions. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Unstable equilibrium [/COLOR][/SIZE][/FONT][/B] One in which any deviation of the object from its equilibrium position results in a force pushing it even farther away. [B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]V[/COLOR][/SIZE][/FONT][/CENTER][/B] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Van der Waals force [/COLOR][/SIZE][/FONT][/B] General term for weak attractive intermolecular forces. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Vapor [/COLOR][/SIZE][/FONT][/B] The gaseous state of a substance that is normally in the liquid state. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Variable Resistor[/COLOR][/SIZE][/FONT][/B] Variable resistors are resistors whose resistance can be altered, usually by means of a rotating or sliding contact. They can be used as potential dividers or rheostats. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Vector Quantity [/COLOR][/SIZE][/FONT][/B] A quantity, which needs both magnitude and direction to describe it, is called a vector quantity. Such a physical quantity should also follow the vector law of addition. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Velocity[/COLOR][/SIZE][/FONT][/B] Distance traveled by a body in a particular direction per unit time is called its velocity. It can also be defined as the displacement of the body per unit time. It is a vector quantity. The SI units of velocity are m / s. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Vibration [/COLOR][/SIZE][/FONT][/B] A back and forth motion that repeats itself. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Virtual image[/COLOR][/SIZE][/FONT][/B] An image where light rays appear to originate from a mirror or lens; this image cannot be projected on a screen. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Voltage drop[/COLOR][/SIZE][/FONT][/B] The electric potential difference across a resistor or other part of a circuit that consumes power. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Volt[/COLOR][/SIZE][/FONT][/B] The volt is the SI unit of voltage. In fact 1 V = 1 JC-1 (i.e. a charge of one coulomb will gain or lose one joule of potential energy when moved through a potential difference of one volt). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Voltmeter[/COLOR][/SIZE][/FONT][/B] A device for measuring voltage differences. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Voltage [/COLOR][/SIZE][/FONT][/B] Electrical potential energy per unit charge that will be possessed by a charged particle at a certain point in space. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Voltage Divider [/COLOR][/SIZE][/FONT][/B] A simple circuit branch consisting of two resistors connected in series. The voltage across the terminals of the branch is shared between the two resistors, with the bigger resistor getting the biggest share. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Voltage Gain[/COLOR][/SIZE][/FONT][/B] Voltage gain has no units of its own. It expresses how many times greater the output signal voltage is (from some component) compared to the input voltage. A closely related concept is that of power gain. Voltage Gain = Output Voltage / Input Voltage. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"] Vector [/COLOR][/SIZE][/FONT][/B] A quantity that has both an amount (magnitude) and a direction in space. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"] W[/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Watt[/COLOR][/SIZE][/FONT][/B] The watt (W) is the SI Unit of power. It is equivalent to one joule per second (Js-1). [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave-particle duality[/COLOR][/SIZE][/FONT][/B] The idea that light is both a wave and a particle. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave function[/COLOR][/SIZE][/FONT][/B] The numerical measure of an electron wave, or in general of the wave corresponding to any quantum mechanical particle. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave mechanics[/COLOR][/SIZE][/FONT][/B] Alternate name for quantum mechanics derived from the wavelike properties of subatomic particles. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave motion[/COLOR][/SIZE][/FONT][/B] The movement of a disturbance produced in one part of a medium to another involving the transfer of energy but not the transfer of matter is called wave motion. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave period[/COLOR][/SIZE][/FONT][/B] The time required for two successive crests of the wave to pass a given point. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave velocity[/COLOR][/SIZE][/FONT][/B] The distance traveled by a wave in one second is called the wave velocity. The wave velocity of a wave depends upon the nature of the medium through which it passes. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wave[/COLOR][/SIZE][/FONT][/B] A disturbance or oscillation that moves through a medium. [IMG]http://www.bbc.co.uk/scotland/education/bitesize/higher/img/physics/radiation/waves/waves1.gif[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wavelength [/COLOR][/SIZE][/FONT][/B] This is the length of a wave between any two equivalent points. It is easiest to measure from crest to crest or from trough to trough. The SI unit of wavelength is the metre, although kilometres, millimetres, micrometres and nanometres are also used. [IMG]http://science.hq.nasa.gov/kids/imagers/ems/wave_crest.gif[/IMG] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Weak nuclear force[/COLOR][/SIZE][/FONT][/B] The force responsible for beta decay. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Weight[/COLOR][/SIZE][/FONT][/B] The force with which a body is attracted towards the center of the earth is called its weight. The SI unit of weight is N. The gravitational units of weight are kg-wt and g-wt. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Weightlessness [/COLOR][/SIZE][/FONT][/B] The state when the apparent weight of a body becomes zero is called the state of weightlessness. All objects while falling freely under the action of gravity appear weightless. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Wind Turbine[/COLOR][/SIZE][/FONT][/B] A device for converting wind energy into mechanical (windmill) or electrical energy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Work[/COLOR][/SIZE][/FONT][/B] When a force acts on a moving object, that force does mechanical work. The work done is defined by the equation: Work Done = Force x Distance The SI unit of work is the same as that of energy - the joule. |
[B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]X [/COLOR][/SIZE][/FONT][/CENTER][/B]
[B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]X-rays[/COLOR][/SIZE][/FONT][/B] X-rays were discovered accidentally by Wilhelm Röntgen in 1895. X-ray radiation is a part of the electromagnetic spectrum. With wavelengths ranging from about 0.001nm to about 100 nm, X-rays are much shorter than ultraviolet. They travel at the speed of light. [B][CENTER][FONT="Comic Sans MS"][SIZE="6"][COLOR="Blue"]Z[/COLOR][/SIZE][/FONT][/CENTER][/B] [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Zenith[/COLOR][/SIZE][/FONT][/B] The zenith is the point in the sky directly above an observer's head. This term is often used in astronomy. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Zeroth law of thermodynamics [/COLOR][/SIZE][/FONT][/B] If body A is in thermal equilibrium with body B, and B is also in thermal equilibrium with C, then A is necessarily in thermal equilibrium with C. This is equivalent to saying that thermal equilibrium obeys a transitive mathematical relation. [B][FONT="Comic Sans MS"][SIZE="4"][COLOR="Blue"]Z boson [/COLOR][/SIZE][/FONT][/B] A carrier particle of weak interactions. It is involved in all weak processes that do not change flavor. |
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