# MCQs / Compilation of Physics Problems Part 6 MCQs / Compilation of Physics Problems
PRACTICE TEST IN PHYSICS SET 6

1. The equation applicable in the adiabatic process of n mole ideal gas is...
A. ΔU = nCpΔT
B. ΔU = nCvΔT
C. ΔQ = nCvΔT
D. ΔQ = nCpΔT

2. In a Carnot's engine, the working substance is...
A. ideal gas
B. steam
C. petrol
D. CO2

3. Two particles A and b initially at rest, move towards each other under a mutual force of attraction. At the instant when the speed of A is v and the speed of B is 2v, the speed of centre of mass of the system is
A. zero
B. v
C. 1.5v
D. 3v

4. Imagine a light planet revolving around a very massive star in a circular orbit of radius R with a period of revolution T. The gravitational force of attraction between the planet and the star is proportional to R(-5/2), then T2 is proportional to...
A. R3
B. R(7/2)
C. R(3/2)
D. R3.75

5. Electrical conductivity increases with the increase in temperature of...
A. P-type semiconductor
B. N-type semiconductor
C. intrinsic semiconductor
D. none

6. Amount of charge in coulomb required to deposit one gram equivalent of substance by electrolysis is...
A.  96500
B.  48 x 10-10
C. 6 x 1024
D. 9600

7. A camera lens is adjusted to f/4 and has an effective diameter of 2.0 cm. Its focal length is...
A. 0.2 cm
B. 1.6 cm
C. 2.0 cm
D. 8.0 cm

8. The self inductance of a long solenoid is directly affected by changes in all but...
A. the number of turns
B. the current
C. the area of cross section
D. the relative permeability of the core

9. Which of the following is not the unit of energy ?
A. joule
B. erg
C. newton.metre
D. dyne

10. All collisions conserve...
A. kinetic energy
B. momentum
C. both kinetic energy and momentum
D. neither of kinetic energy and momentum

11. If a rocket of initial mass m is to rise from its launching pad, its initial thrust must exceed...
A. mg/2
B. mg
C. 2mg
D. mg2/2

12. 9 gram of water contains approximately...
A. 6 x 1023 molecules of water
B. 6 x 1023 atoms of oxygen
C. 6 x 1023 atoms of hydrogen
D. 3 x 1023 atoms of hydrogen

13. A cable can support a maximum load of W without exceeding the elastic limit. If it is replaced by a cable of same material but half as long and half the diameter, the elastic limit will not be exceeded by the new cable up to a load of...
A. W/4
B. W/2
C. W
D. 2W

14. Surface tension does not depend on...
A. surface area
B. the type of liquid
C. temperature
D. medium in contact with the liquid

15. -40° F is equal to...
A. -40° C
B. -8° C
C. -72° C
D. -104° C

16. The magnitude of the field within a conductor...
A. depends on the shape of the conductor
B. is always zero
C. is always positive
D. may be zero or positive

17. A permanent magnet does not exert force on...
A. an unmagnetized iron bar
B. a magnetized iron bar
C. a stationary electric charge
D. a moving electric charge

18. A primary rainbow cannot be seen by an observer looking up if the altitude of the Sun exceeds...
A. 10°
B. 20°
C.  22.5°
D.  40°

19. According to the descending order of temperature the stars are classified in to the orders O,B,A,F,G,K and M. Our Sun comes in the order...
A. A
B. B
C. G
D. K

20. Position of the centre of mass of a rigid body depends on...
A. its shape only
B. distribution of its matter only
C. both its shape and distribution of matter
D. its position relative to the earth.

21. Force is to linear motion as _____ is to rotational motion.
A. acceleration
B. torque
C. moment of inertia
D. angular momentum

22. A hole is drilled to the centre of the earth and a stone is dropped in to it. When the stone is at the earth's centre, compared to the values at the earth's surface...
A. its mass and weight both change
B. its mass and weight both are zero
C. its mass is unchanged and its weight is zero
D. its mass is zero and its weight is unchanged

23. For an IC engine, the thermal efficiency depends on...
A. the compression ratio
B. the speed of the piston
C. the temperature of working medium
D. the diameter of the cylinder

24. A 12-V potential difference is applied across a series combination of four 6-ohm resistors. The current in each resistor is...
A. 0.5 A
B. 2 A
C. 8 A
D. 18 A

25. The temperature at which the thermo emf becomes zero is known as the...
A. neutral temperature
B. absolute temperature
C. inverse temperature
D. thermoelectric temperature

26. A transformer uses the principle of...
A. self-induction
B. mutual induction
C. variable resistance
D. electrostatic attraction

27. If V and Vm are the instantaneous and maximum values, respectively , of voltage in an a.c. circuit, then the mean value of the voltage is...
A. Vm sinωt
B. √ 2 Vm
C. Vm/√ 2
D. none of the above

28. Electromagnetic waves having wavelengths greater than 200 m are called...
A. sky waves
B. ground waves
C. micro waves
D. X-rays

29. If θm is the angle of diffracted wave with the direction of incidence and d is the width of slit, then mth order minima is obtained for sinθm equal to...
A. mλ/d
B. dλ/m
C. md/λ
D. m/λd

30. As a sample of a radioactive element decays, its half-life...
A. decreases
B. increases
C. remains the same
D. changes exponentially.