MCQ Questions for Class 9 Science: Ch 12 Sound

MCQ Questions for Class 9 Science: Ch 12 Sound

1. Sound is produced by _________objects.
(a) fast moving
(b) vibrating
(c) stationary
(d) rotating
► (b) vibrating

2. A key of mechanical piano is first struck gently and then struck again but much harder this time. What kind of change in sound will you observe in the second case:
(a) Sound will be louder but the pitch will not be different
(b) Sound will be louder and the pitch will also be higher
(c) Sound will be louder but the pitch will be lower
(d) Both loudness and pitch will remain unaffected
► (c) Sound will be louder but the pitch will be lower

3. In case of transverse waves the particles of a medium vibrate:
(a) In the direction of wave propagation
(b) Opposite to the direction of wave propagation
(c) At the right angles to the direction of wave propagation
(d) None of the above
► (c) At the right angles to the direction of wave propagation

4. The upper frequency limit of the audible range of human hearing is about
(a) 20 kHz
(b) 2000 Hz
(c) 2 kHz
(d) 2,000,000 Hz
► (a) 20 kHz

5. The distance between a consecutive crest and trough is x. The wavelength of the wave is
(a) 4x  
(b) x
(c) x/2
(d) 2x
► (d) 2x

6. Sound wave is a
(a) transverse wave
(b) longitudinal wave
(c) both a and b
(d) None of these
► (b) longitudinal wave

7. You can not talk to each other on the moon because
(a) atmosphere is not present, that is, there is vacuum
(b) you would not feel like talking
(c) compressions and rarefactions can only travel on earth’s surface
(d) gravity is 1/6th that on the earth
► (a) atmosphere is not present, that is, there is vacuum

8. Sonic booms are caused by the combination of
(a) supersonic speed and pressure variation.
(b) infrasonic speed and pressure variation.
(c) ultrasonic sound and pressure variation.
(d) pressure variation only.
► (a) supersonic speed and pressure variation.

9. Frequency of infrasonic waves is ____________ than frequency of ultrasound waves.
(a) less
(b) more
(c) almost same
(d) none of these.
► (a) less

10. Sound travels
(a) slower in warm air than in cold air
(b) faster in solids and liquids than in air
(c) slower in water than air
(d) none of these
► (b) faster in solids and liquids than in air

11. In longitudinal waves, how does the particle of medium vibrate compared to the direction of propagation of wave?
(a) Perpendicular
(b) Parallel
(c) At 45°
(d) At 60°
► (b) Parallel

12. The sound waves in a medium are characterised by the:
(a) Linear motion of particles in the medium
(b) Rotatory motion of particles in the medium
(c) Oscillatory motion of particles in the medium
(d) None of the above
► (c) Oscillatory motion of particles in the medium

13. Sound can travel through
(a) gases only
(b) vacuum only
(c) gases and liquids only
(d) solids, liquids and gases.
► (d) solids, liquids and gases.

14. The motion of the particles of a medium when a sound wave is passing through it is:
(a) translatory
(b) random
(c) rotatory
(d) oscillatory
► (d) oscillatory

15. The transfer of energy in a material medium due to the periodic motion of its particles is called:
(a) Wave front
(b) Wave motion
(c) Pulse
(d) None of the above
► (b) Wave motion

16. A wave moves a distance of 10m in 0.05 second. Find the wavelength of the wave if frequency is 200Hz?
(a) 0.8M
(b) 1m
(c) 0.5m
(d) 0./m
► (b) 1m

17. The maximum displacement of the particle of the mean from its mean position is called the
(a) Amplitude
(b) wavelength
(c) wave number
(d) none of these
► (a) Amplitude

18. Which of the following is a mechanical wave?
(a) Sound
(b) Light
(c) Radio waves
(d) X-rays
► (a) Sound

19. Wave motion transfers
(a) momentum
(b) velocity
(c) energy
(d) mass
► (c) energy

20. The longitudinal waves can propagate only in :
(a) Solids
(b) Liquids
(c) Gases
(d) All the above
► (d) All the above

21. The sound waves which travel in the air are called:
(a) Transverse waves
(b) Longitudinal waves
(c) Polarised waves
(d) None of the above
► (b) Longitudinal waves

22. Infrasonic waves have frequencie
(a) below 20 Hz
(b) between 20 Hz and 20,000 Hz 
(c) above 20,000 Hz
(d) no upper or lower limit of frequencies
► (a) below 20 Hz

23. In the compression region of the medium in case of longitudinal wave:
(a) The volume monetarily decreases
(b) The density momentarily
(c) The pressure monetarily increases
(d) All the above
► (d) All the above

24. Which wave property determines loudness?
(a) pitch
(b) frequency
(c) amplitude
(d) All of these
► (c) amplitude

25. Which is not the condition for hearing sound?
(a) There must be a vibrating body capable of transferring energy
(b) There must be a material medium to pick up and propagate energy
(c) The medium must have a large density
(d) There must be receiver to receive the energy and interpret it
► (c) The medium must have a large density

26. In case of transverse wave :
(a) The hump on the + y axis is called crest
(b) The hump on the – y axis is called crest
(c) The highest point on the hump on + y axis is called crest
(d) The highest point on the hump on the – y axis is called crest
► (c) The highest point on the hump on + y axis is called crest

27. Sound cannot travel throug
(a) air
(b) water
(c) iron
(d) space
► (d) space

28. In the bell jar experiment, as air is removed
(a) intensity falls
(b) speed of sound falls
(c) both (a) and (b)
(d) elasticity falls
► (a) intensity falls

29. A bat hears the echo of its squeak after 0.1 second. How far is the obstacle from the bat? Speed of sound is 344 m/s.
(a) 170m
(b) 17.2m
(c) 180m
(d) 18m
► (b) 17.2m

30. The method of detecting the presence, position and direction of motion of distant objects by reflecting a beam of sound waves is known as _____.
(a) RADAR
(b) SONAR
(c) MIR
(d) CRO
► (b) SONAR

31. Which of the following is not the character of mechanical waves ?
(a) Propagation depends on the elasticity of medium
(b) Can be both transverse or longitudinal
(c) Requires a material medium
(d) Speed is comparatively higher
► (d) Speed is comparatively higher

32. A thunder clap is heard 5.5 seconds after lightning flash. The distance of the flash is (Velocity of sound in air = 330 m/s)
(a) 1750 m
(b) 1815 m
(c) 3000 m
(d) 3500 m
► (b) 1815 m

33. In the region of compression or rarefaction, in a longitudinal wave the physical quantity which does not change is:
(a) Pressure
(b) Mass
(c) Density
(d) Volume
► (b) Mass

34. A part of longitudinal wave in which particles of medium are farther away than the normal particles is called:
(a) Rarefaction
(b) Trough
(c) Compression
(d) Crest
► (a) Rarefaction
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