PUNJAB PUBLIC SERVICE COMMISSION
COMBINED COMPETITIVE EXAMINATION FOR
RECRUITMENT TO THE POSTS OF
PROVINCIAL MANAGEMENT SERVICE, ETC. – 2015
SUBJECT: PHYSICS (PAPER-II)
TIME ALLOWED: THREE HOURS
MAXIMUM MARKS: 100
Note: Attempt any FIVE questions selecting at least ONE from each Section.All questions carry equal marks. Attempt in English Language.
SECTION-I
Q.1. a). Derive a formula for the magnetic force, acting on a current carrying conductor placed in a non-uniform magnetic field.
b). A copper wire having mass of 50 grams/m is placed in a uniform magnetic field of strength 0.1 T, such that the wire floats in the field. Calculate the current flowing in the wire.
Q.2. a). apply Ampere’s law to calculate the magnetic field in the interior of a current carrying toroid (circular solenoid ).
b). A solenoid has 100 turns per centimeter. An electron moves within the solenoid in the a circle of radius 2.3 cm perpendicular to the axis of the solenoid . If the speed of the electron is 0.05c. Find the Current .
[e=1.6 x 10-19C; me =9.1x10-31 kg ; µo= 4 π x10-7 NA-2
SECTION-II
Q.3. a). describe in detail a common emitter transistor, when used as an amplifier.
b). Determinate the relationship for voltage gain and power gain for this amplifier.
C). Explain in detail a Full-wave bridge rectifier.
Q.4. a). Sate DeMorgan’s theorem to the following:
i. (A+B+C)D
ii. (ABC+DEF)
iii. AB+CD+EF
Q.5. Write in detail on nay one of the following, laying emphasis on experimental verification of the phenomenon.
i. Photoelectric Effect
ii. Compton Scattering
iii. De Broglie Hypothesis
b) Find the maximum speed of photoelectrons emitted from a material whose work function is 2.33eV when irradiated electromagnetic radiation of frequency 4.09x 1015 Hz.
Q.6. a). Derive the equation of radioactive decay A=Ao e -^Ɨ, Where A is Activity, ƛ the decay constant and t the time.
b) Use the equation above to drive a formula for calculating the half-life.
c). A rock sample contains 1.0 mg of 206pb and 4.0 mg of 238U.
Q.7. Write Note on any two of the following.
i. Zeeman Effect
ii. Heisenberg’s Uncertainty principle.
iii. Negative feedback in operation amplifiers
iv. Amplitude and frequency Modulation