Sound and Waves CDS Questions

CDS Physics

Sound and Waves MCQ Questions


13.
When two sound waves of slightly different frequencies superpose, the resulting periodic rise and fall in the loudness of the combined sound is called:
A.
Reverberation
B.
Echo
C.
Beats
D.
Resonance
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ANSWER :
C. Beats
14.
When a wave passes from one medium into another, which of its characteristics remains unchanged, while its speed and wavelength generally change?
A.
Speed of the wave
B.
Frequency
C.
Amplitude in all cases
D.
Wavelength
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ANSWER :
B. Frequency
15.
The energy carried by a mechanical wave is directly proportional to:
A.
Its time period alone
B.
The inverse of its frequency
C.
The square of its amplitude
D.
Its wavelength alone
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ANSWER :
C. The square of its amplitude
16.
The Doppler effect refers to:
A.
A permanent change in the actual frequency emitted by a stationary source
B.
The splitting of white light into its constituent colours
C.
The bending of waves as they pass around an obstacle
D.
The apparent change in the observed frequency of a wave due to relative motion between the source and the observer
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ANSWER :
D. The apparent change in the observed frequency of a wave due to relative motion between the source and the observer
17.
The Doppler effect was first explained, for sound waves, by which scientist?
A.
Christiaan Huygens
B.
Heinrich Hertz
C.
James Clerk Maxwell
D.
Christian Doppler
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ANSWER :
D. Christian Doppler
18.
When a sound source moves towards a stationary observer, the apparent frequency heard by the observer:
A.
Increases, so the sound appears to have a higher pitch
B.
Decreases, so the sound appears to have a lower pitch
C.
Drops instantly to zero
D.
Stays exactly equal to the source's actual frequency
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ANSWER :
A. Increases, so the sound appears to have a higher pitch