Sound MCQs
Matric · Physics (10th) · 6 questions
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10th class physics: Sound
Sound is a longitudinal wave made by vibrating objects, and it needs a medium: it cannot cross a vacuum. It travels fastest in solids (about 5,000 m/s in steel), slower in liquids (about 1,500 m/s in water) and slowest in gases (about 340 m/s in air). Three characteristics describe a sound. Loudness depends on amplitude (and is measured in decibels); pitch depends on frequency; quality (timbre) depends on the overtones mixed in, which is why a flute and a violin playing the same note sound different. Humans hear roughly 20 Hz to 20,000 Hz; lower frequencies are infrasound and higher ones ultrasound, which is used in medical scans, sonar and cleaning. An echo is reflected sound; because the ear holds a sound for about 0.1 s, a distinct echo needs a reflecting surface at least about 17 m away in air. Noise pollution and acoustic protection (soft, porous materials absorb sound) are common short questions.
Questions with answers
Written by Parcha from the syllabus. Samples until a subject reviewer checks them; report anything wrong from the practice screen.
Q1 · Parcha original · Sample
Sound travels fastest in:
- A. Steel
- B. Water
- C. Air
- D. A vacuum
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Answer: A. Steel
Sound is fastest in solids, slower in liquids and slowest in gases: roughly 5,000 m/s in steel, 1,500 m/s in water and 340 m/s in air. It cannot travel through a vacuum at all.
Open this question on its own pageQ2 · Parcha original · Sample
The audible frequency range for a normal human ear is about:
- A. 2 Hz to 2,000 Hz
- B. 200 Hz to 200,000 Hz
- C. 20 Hz to 20,000 Hz
- D. 0 Hz to 2 Hz
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Answer: C. 20 Hz to 20,000 Hz
People with normal hearing hear about 20 Hz to 20,000 Hz (20 kHz). Below 20 Hz is infrasound; above 20 kHz is ultrasound.
Q3 · Parcha original · Sample
Ultrasound has frequencies:
- A. Below 20 Hz
- B. Between 20 Hz and 2,000 Hz
- C. Exactly 20 kHz
- D. Above 20 kHz
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Answer: D. Above 20 kHz
Ultrasound is sound above the upper limit of human hearing, 20 kHz. It is used in medical scans, cleaning and sonar.
Q4 · Parcha original · Sample
The loudness of a sound depends mainly on its:
- A. Frequency
- B. Amplitude
- C. Wavelength alone
- D. Speed
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Answer: B. Amplitude
A larger amplitude carries more energy, so the sound is louder. Frequency decides the pitch, not the loudness.
Q5 · Parcha original · Sample
The pitch of a sound depends on its:
- A. Frequency
- B. Amplitude
- C. Loudness
- D. Quality
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Answer: A. Frequency
Higher frequency means higher pitch: a whistle sounds shrill because of its high frequency. Amplitude affects loudness, and the mix of overtones gives quality (timbre).
Q6 · Parcha original · Sample
To hear a distinct echo in air (speed of sound 340 m/s), the reflecting surface must be at least about how far away?
- A. 34 m
- B. 10 m
- C. 17 m
- D. 170 m
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Answer: C. 17 m
The ear keeps a sound for about 0.1 s, so the echo must return after at least 0.1 s. In 0.1 s sound travels 340 × 0.1 = 34 m there and back, so the surface must be at least 17 m away.