# MCQs / Compilation of Physics Problems Part 3 MCQs / Compilation of Physics Problems
PRACTICE TEST IN PHYSICS SET 3

1. In simple harmonic motion, there is always a constant ratio between the displacement of mass and its...
A. speed
B. acceleration
C. period
D. mass

2. The wave intensity is proportional to the...
A. amplitude
B. square of amplitude
C. frequency
D. square of frequency

3. When a rigid body rotates about an axis and the external torque is zero, then for that body is constant.
A. angular velocity
B. moment of inertia
C. linear momentum
D. angular momentum

4. If Q1 is the heat absorbed by the working substance and Q2 is the heat utilized in doing work, then the efficiency of the engine is given by...
A.  1 - (Q1/Q2)
B.  1 - (Q2/Q1)
C.  (1 - Q1)/Q2
D.  (1 - Q2)/Q1

5. Two identical resistors in parallel have an equivalent resistance of 2 Ω. If the resistors were in series, their equivalent resistance would be...
A. 2 Ω
B. 4 Ω
C. 8 Ω
D. 16 Ω

6. The value of permeability of vacuum (μ) in tesla.m/ampere is...
A. 4 x 10-7
B. 4π x 10-7
C. 1.257 x 10-6
D.  1.257 x 106

7. The power factor of a circuit in which XL = XC...
A. is 0
B. is 1
C. depends on XL/XC
D. depends on R

8. It is impossible to polarize...
A. white light
C. X-rays
D. sound waves

9. The wave theory of light fails to explain...
A. interference
B. diffraction
C. polarization

10. The beta- disintegration of a parent element produces a daughter element which in the periodic table is...
A. up by one step
B. down by one step
C. up by two steps
D. down by two steps

11. The unit of radioactive constant(λ) of the disintegrating element is...
A. m
B. m/s
C. s-1
D. m-1

12. The process of introducing impurity in an intrinsic semiconductor is called...
A. diffusion
B. doping
C. depletion
D. transition

13. Which of the following is dimensionless?
A. frequency
B. stress
C. coefficient of friction
D. gas constant

14. When the acceleration is zero, the final velocity of the object is...
A. zero
B. less than initial velocity
C. more than initial velocity
D. equal to initial velocity

15. The coefficient of static friction for steel on ice is 0.1. The coefficient of sliding friction therefore can be
A. 0.08
B. 0.1
C. 0.11
D. 1.1

16. If a shell fired from a cannon explodes in mid-air...
A. its total kinetic energy increases
B. its total kinetic energy decreases
C. its total momentum increases
D. its total momentum decreases

17. Avogadro suggested that the smallest particle of an element that can exist in free state is...
A. atom
B. molecule
C. neutron
D. ion

18. An iron wire 1 m long with a square cross section 2 mm on a side is used to support a 100-kg load. Its elongation is...
A. 0.0027 mm
B. 0.27 mm
C. 1.3 mm
D. 3.7 mm

19. Dimensions of coefficient of surface tension are...
A. M1L1T-2
B. M1L1T1
C. M1L0T-2
D. M1L0T-1

20. A sample of gas is compressed to half its original volume while its temperature is held constant. If the average speed of the gas molecules was originally v, then their new average speed is...
A. 4v
B. v
C. 2v
D. v/2

21. Generally, for a pure metal...
A. Cp = Cv
B. Cv = 3R/2
C. Cp - Cv = R
D. Cv - Cp = R

22. Two 50 µF capacitors are connected in parallel. The equivalent capacitance of the combination is...
A. 25 µF
B. 50 µF
C. 100 µF
D. 200 µF

23. Ferromagnetism is observed...
A. only in crystalline state
B. only in amorphous solid state
C. both in crystalline and amorphous state
D. in any state of the substance

24. The velocities of violet and red lights are Vv and Vr, respectively, then...
A. Vv = Vr in glass
B. Vv = Vr in vacuum
C. Vv > Vr in glass
D. Vv > Vr in vacuum

25. 1 astronomical unit is equal to...
A. 499 light seconds
B. 149597 km
C. 3 x 1010 km
D. 3 x 1010 m

26. The displacement of particles in a string stretched in the x-direction is represented by y. Among the following expressions for y, one that describes wave motion is...
A. coskx sinωt
B. k2x2 - ω2t2
C. cos2(kx + ωt)
D. cos(k2x2 - ω2t2)

27. A boat which has a speed of 5 km/h in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water in km/h is...
A. 1
B. 3
C. 4
D. √ 41

28. If one mole of monoatomic gas (γ = 5/3) is mixed with one mole ofa diatomic gas (γ = 7/5), the value of γ for the mixture is...
A. 1.40
B. 1.50
C. 1.53
D. 3.07

29. The ratio of the inertial mass to gravitational mass is...
A. 0.5
B. 0.2
C. 1
D. g/G

30. On increasing the mass of a body suspended at the end of a spring kept vertically, its period...
A. decreases
B. increases
C. does not change
D. may increase or decrease