Scientific Instruments And Devices

[Saqib Riaz]

Altimeter
an instrument used in aircraft to estimate altitude;its usual essential feature is an aneroid barometer which reegisters the decrease of pressure with height.Roughly 1 millibar corresponds to 9 m.To read an aircraft altimeter correct for its destination, the zero setting must be adjusted for the differnce of ground height and difference of surfac e pressure,especially when pressure is falling or when flying towards low pressure.

Ammeter
is the instrument whch measures electric current,usually in amperes.

Anemometr
is an instrument for measuring wind Speed.

Barometer
Is an instrument used for measuring the pressure of the air.Air presses down on the Earth,pulled by the Earth's gravity. Evangelista Torricelli showed this in 1643.He put a tube in a dish of mercury.This mercury always rose to be height of roughly 76 m (nearly 30 in) in the tube.(The height varies slightly according to the temprature and air pressure). The air was pushing down on the mercury in the dish to forcing it up the tube.This was the first barometer,known as a mercury barometer.It measure air pressure in centimeters of the mercury.Another barometer often used in the aneroid barometer in which air pressure is indicated by a pointer on a dial.The air pressure changes slightly as the weather changes.For Example, a drop in air presure signifies worse weather.bBarometer are thus used in weather forecasting.

Binoculars or field-glasses
Are an optical instrument that basically consists of two small,linked telescope,one for each eye.This make it possible for a viewerto look at distant objects comfortably with both eyes at the same time,and to see a single magnified image.There is usually a screw on the instrument with which the focus can be controlled.Conveniently portable,binoculars have been widely ised during wars,but they have also added to the enjoyment of astronomy bird and animalwatching,sport and theaterically performance.

Calliper

Is the mechanical device used to determine small lengths with reasonable accuracy.Simple calipers have two moveable legs of some desired shap to meet the surface whose sepration is to be measured.The adjusted width between the leg tip is then placed against some length scale.The more comple vernier calliper is wrenchlike and has a scale that allows direct reading of the adjusted width between the jaws of the wrench.

Calorimeter
is and instrument for measuring quantities of heat.

Centrifuge
Is am instrument used to seperate mixtures of chemicals.It spins very quickly.Some centrifuges can spin as fast as 100000 times per minute.Anything put in a centrifuge is pulled out to the side of the centrifuges as its spin.Denser substances are pulled harder than less dense substance.If a mixture is liquid is poured into centrifuges,the denser liquid will will move to the outside and the less dense liquid will stay nearer the middle.In this way liquid,or solid mixed with liquid can be seperated.


Chonometer
Is the device that keeps time with great precision.Historricaly a chronometer was any precision timeplace, but today a watch or clock must be certified by the Controle officiel Suisse des Chronometer (COSC, or Swiss Official Chronometer Testing Institute) to be called a chronometer. Modern chronometer remain virtually unaffected by environmental factors,such as changes in the position and temprature.Most chronometer are abe to keep time with an accuracy of withing three seconds per day; and many chronometer have an accuracy of within 0.1 seconds per day.