Competitive Exams: Physics MCQs (Practice-Test 7 of 35)

  1. If a body of mass m (m is the mass in motion) is moving with a velocity u, then the kinetic energy of the body of rest mass m0 will be

    1. (½) mu2

    2. m0c2

    3. (½) (mc2 − m0u2)

    4. (m-m0) c2

  2. A particle moving with simple harmonic motion through points P and Q with the same velocity. Having taken two seconds in passing from P to Q, it returns to Q after another 2 seconds. The period in seconds is

    1. 2

    2. 4

    3. 6

    4. 8

  3. Two harmonic vibrations X = a sin (wt + f) and Y = b sin (wt) represent the displacement of a particle along X and Y axis, respectively. If the phase difference f p =/2, then the trajectory of the particle will be a/an

    1. ellipse

    2. straight line with positive slope

    3. straight line with negative slope

    4. circle

  4. It is possible to distinguish between transverse and longitudinal waves by studying their

    1. reflection

    2. polarisation

    3. diffraction

    4. interference

  5. Which one of the following equations represents a stationary wave?

    1. Y = 2a sin (2p t/T) cos 2p (x/l)

    2. Y = a sin 2 pn (t-x/) l

    3. Y = a sin wt

    4. Y = a sin2 { (t/T) - (x/}) l

  6. A tuning fork ‘X’ of unknown frequency when sounded together with another tuning fork ‘Y’ of frequency 480 Hz gives 4 beats per second. When it is loaded with wax, if it still gives 4 beats/sec, then the frequency of the tuning fork ‘X’ is

    1. 476 Hz

    2. 480 Hz

    3. 484 Hz

    4. 486 Hz

  7. The equations yl = al sin w1t and y2 = a2 sin w2t represent two waves. If w1 − w2 is small, then the amplitude of the beats heard will vary from

    1. zero to a1 + a2

    2. zero to a1 − a2

    3. (al-a2)/2 to (al + a2)/2

    4. al-a2 to al + a2

  8. An engine blowing its whistle at a frequency of 1200 Hz approaches a stationary observer with a velocity of 50 ms-1. If the speed of sound is 350 ms-1, then the apparent frequency as heard by the observer is

    1. 1400 Hz

    2. 1200 Hz

    3. 1050 Hz

    4. 600 Hz

  9. The angular frequency of motion whose equation is 4 (d2y/dt2) + 9y = 0 is (y is displacement and t = time)

    1. 9/4

    2. 4/9

    3. 3/2

  10. With symbols having the usual meanings, which one of the following expressions correctly represents forced oscillation?

    1. (d2y/dt2) + w2y = 0

    2. d2y/dt2 = 0

    3. d2y/dt2 + 2k (dy/dt) + w2y = 0

    4. d2y/dt2 + 2k (dy/dt) + w2y = F sin pt

  11. Acoustic grating is obtained by

    1. ruling a glass plate

    2. ruling a cellulose plate

    3. sending ultrasonics through a fluid

    4. ruling a plastic sheet

  12. If there is no transmission of energy in the medium, then the propagated wave is a/an

    1. electromagnetic wave

    2. longitudinal wave

    3. transverse wave

    4. stationary wave

  13. Which one of the following vibrating systems can oscillate under resonance?

    1. Two pendulums of equal length suspended from a rigid support

    2. Two pendulums of equal length suspended from a flexible support

    3. Two pendulums of unequal length suspended from a rigid support

    4. Two pendulums of unequal lengths suspended from a flexible support

  14. Match List I with List II and select the correct answer

    List-I (Microphone) List-II (Principle)
    1. Capacitor microphone

    2. Crystal microphone

    3. Carbon microphone

    4. Ribbon microphone

    1. Change in resistance

    2. Induced emf

    3. Change in voltage

    4. Change in electrical energy

    • A
    • B
    • C
    • D
      • 4
      • 3
      • 2
      • 1
      • 3
      • 4
      • 2
      • 1
      • 3
      • 4
      • 1
      • 2
      • 4
      • 3
      • 1
      • 2
  15. Match List I with List II and select the correct answer

    List-I List-II
    1. Velocity of sound in air

    2. Analysis of complex sound

    3. Frequency of a fork

    4. Young's modulus of a rod

    1. Kundt's tube

    2. Sonometer

    3. Helmholtz resonator

    4. Resonance column apparatus

    • A
    • B
    • C
    • D
      • 4
      • 3
      • 2
      • 1
      • 4
      • 3
      • 1
      • 2
      • 3
      • 4
      • 2
      • 1
      • 3
      • 4
      • 1
      • 2