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Waves
Written by Dr. Hamza Farooq (Physics)
8 Class 11 Physics questions with answers and explanations.
Printable worksheet with answer key
All questions with answers
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The speed of a wave of frequency 100 Hz and wavelength 3.4 m is:
- 1 340 m/s
- 2 3.4 m/s
- 3 34 m/s
- 4 103.4 m/s
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Correct answer: 340 m/s
v = f x wavelength = 340 m/s.
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The beat frequency of two sources of 256 Hz and 260 Hz is:
- 1 2 Hz
- 2 4 Hz
- 3 258 Hz
- 4 516 Hz
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Correct answer: 4 Hz
Beat frequency = difference = 4 Hz.
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In a stationary wave the points of zero amplitude are:
- 1 Wavefronts
- 2 Nodes
- 3 Crests
- 4 Antinodes
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Correct answer: Nodes
Nodes are the points where the amplitude is zero.
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The Doppler effect is a change in the observed:
- 1 Mass
- 2 Amplitude only
- 3 Frequency due to relative motion
- 4 Speed of light
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Correct answer: Frequency due to relative motion
Relative motion of source and observer changes the observed frequency.
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The fundamental frequency of a string of length L and wave speed v fixed at both ends is:
- 1 2 v / L
- 2 v / 2L
- 3 v / L
- 4 v L
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Correct answer: v / 2L
The string holds half a wavelength: f = v / 2L.
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The speed of a wave on a stretched string increases when the tension:
- 1 Increases
- 2 Is zero
- 3 Decreases
- 4 Is constant
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Correct answer: Increases
v = square root of (T / mu).
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Sound is a:
- 1 Transverse wave only
- 2 Electromagnetic wave
- 3 Surface wave only
- 4 Longitudinal wave
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Correct answer: Longitudinal wave
Particles vibrate along the direction of travel.
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Constructive interference occurs when two waves meet:
- 1 In phase
- 2 At right angles
- 3 At different speeds
- 4 Out of phase by 180 degrees
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Correct answer: In phase
Crests meet crests.
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