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Frequency & Amplitude — Homi Bhabha Class 9 Physics MCQs with Solutions
Free Homi Bhabha Class 9 Physics Frequency & Amplitude MCQs with step-by-step solutions (10 questions). Part of Sound. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Frequency & Amplitude · medium · theory
The pitch (shrillness) of a sound depends on its:
A. amplitude
B. wavelength only
C. speed
D. frequency ✓ Correct
Solution: Higher frequency gives a higher pitch; loudness depends on amplitude.
Q2 — Frequency & Amplitude · medium · theory
The loudness of a sound depends on its:
A. frequency
B. amplitude ✓ Correct
C. pitch
D. speed
Solution: A larger amplitude means a louder sound; pitch depends on frequency.
Q3 — Frequency & Amplitude · medium · numerical
A tuning fork vibrates 480 times in 2 s. Its frequency is:
A. 120 Hz
B. 960 Hz
C. 480 Hz
D. 240 Hz ✓ Correct
Solution: Frequency $= \dfrac{\text{number of vibrations}}{\text{time}} = \dfrac{480}{2} = 240$ Hz.
Q4 — Frequency & Amplitude · hard · numerical
A sound wave has a speed of 340 m/s and a frequency of 170 Hz. Its wavelength is:
A. 0.5 m
B. 510 m
C. 2.5 m
D. 2 m ✓ Correct
Solution: Wavelength $= \dfrac{v}{f} = \dfrac{340}{170} = 2$ m.
Q5 — Frequency & Amplitude · hard · numerical
The time period of a wave of frequency 250 Hz is:
A. 250 s
B. 0.04 s
C. 0.004 s ✓ Correct
D. 0.25 s
Solution: Time period $= \dfrac{1}{f} = \dfrac{1}{250} = 0.004$ s.
Q6 — Frequency & Amplitude · hard · theory
Two sounds have the same loudness, but one is shriller than the other. The shriller sound has a greater:
A. frequency ✓ Correct
B. speed
C. time period
D. amplitude
Solution: Shrillness (pitch) is decided by frequency; equal loudness means equal amplitude.
Q7 — Frequency & Amplitude · easy · theory
The loudness of a sound depends mainly on which property of the sound wave?
A. Its frequency
B. Its speed
C. Its wavelength
D. Its amplitude ✓ Correct
Solution: A larger amplitude means the particles vibrate with more energy, which the ear senses as a louder sound. Frequency controls pitch, not loudness.
Q8 — Frequency & Amplitude · medium · numerical
A sound wave of frequency 500 Hz travels through air at 340 m/s. What is its wavelength?
A. 170 m
B. 1.47 m
C. 0.68 m ✓ Correct
D. 0.34 m
Solution: Using speed = frequency x wavelength, wavelength = speed / frequency = 340 / 500 = 0.68 m.
Q9 — Frequency & Amplitude · medium · numerical
A vibrating tuning fork completes one full vibration in 0.004 s. What is its frequency?
A. 400 Hz
B. 250 Hz ✓ Correct
C. 4000 Hz
D. 25 Hz
Solution: Frequency is the reciprocal of the time period: frequency = 1 / T = 1 / 0.004 = 250 Hz.
Q10 — Frequency & Amplitude · hard · numerical
A sound wave in air has a speed of 340 m/s and a wavelength of 0.5 m. If, in the same air, the frequency of the source is doubled, what is the new wavelength?
A. 0.5 m
B. 0.125 m
C. 0.25 m ✓ Correct
D. 1.0 m
Solution: Speed depends only on the medium, so it stays 340 m/s. Since speed = frequency x wavelength is constant, doubling the frequency halves the wavelength: 0.5 / 2 = 0.25 m.