Physics · Science General

Acoustics and Sound Waves

2,160 Questions

Acoustics and sound waves deal with mechanical vibrations traveling through media like air and water. Key concepts include wave reflection, beats, echoes, the Mach number, and infrasound. These physics fundamentals are regularly tested in general science sections of multiple competitive exams.

Sound wave propagationEchoes and reflectionWave interferenceMach numberInfrasound frequency

Acoustics and Sound Waves Questions

Multiple choice

Which of the following statements is false?

  1. When we pluck the strings of a guitar, the only sound we hear is the sounds of the vibrating strings.

  2. When we strike a drum, the sound we hear is the sound of the stretched membrane as well as of the body of the drum.

  3. When we pluck the strings of a sitar, the sound we hear is that of the body as well as the strings.

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When we pluck the strings of a guitar, the only sound we hear is the sounds of the vibrating strings as well as the sound of the vibrating body.

Multiple choice

Which of the following statements is false?

  1. Sound can travel though liquids.

  2. Sound can travel through gases.

  3. Sound can travel through solids.

  4. Sound cannot travel through all solids, liquids or gases.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sound can travel through all solids, liquids or gases. Hence, option (4) is false.

Multiple choice

What is the correct pathway of sound through ear?

  1. Outer ear – ear drum – ear canal – inner ear – brain

  2. Outer ear – ear canal – ear drum – inner ear – brain

  3. Outer ear – ear drum – inner ear – ear canal – brain

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sound enters the outer ear, travel downs the ear canal and strikes the ear drum. The ear drum sends the vibrations to the inner ear, from where the signal goes to the brain. Hence, option (2) is correct.

Multiple choice

Which of the following statements is false?

  1. A drum produces a low pitched sound because it vibrates with a low frequency.

  2. A whistle has a high frequency and therefore, produces a sound of a higher pitch.

  3. A loud roar of a lion is low pitched and has a high amplitude.

  4. A bird makes a feeble high pitched sound, which has a high frequency and amplitude.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The loudness of a sound depends upon its amplitude. The higher the amplitude, the louder is the sound and vice-versa. The pitch or shrillness of a sound is determined by its frequency. The higher the frequency, the shriller is the sound and vice-versa. Hence, option (4) is false. A feeble sound will have a low amplitude, not a high amplitude. 

Multiple choice

Sounds of the following amplitudes and frequency are given as measured. Identify the loudest sound and the shrillest sound.

(a) 60 dB, f (b) 65 dB, 4f (c) 75 dB, 2f (d) 80 dB, 3f

  1. (a), (b)

  2. (b), (c)

  3. (a), (c)

  4. (d), (b)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The loudness of a sound depends upon its amplitude. The higher the amplitude, the louder the sound and vice-versa. The pitch or shrillness of a sound is determined by its frequency. The higher the frequency, the shriller the sound and vice-versa. Hence, option (4) is correct.

Multiple choice

Sound from a source A is measured to be 20 dB, while that from a source B is measured to be 80 dB. If the amplitude of sound at A is a, then the amplitude of sound at B is

  1. 2a

  2. 4a

  3. 16a

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Loudness of a sound is proportional to the square of its amplitude. Hence, let amplitude of the sound of 20 dB be a. Then, 20 = ka2; Sound of 80 dB = kb2 (where b is the amplitude of sound at B). i.e. 4ka2 = kb2 i.e. k(2a)2 = kb2 Hence, b = 2a. Thus, amplitude at B is double of that at A.

Multiple choice

Which of the following statements is false?

  1. Installation of silencing devices in home appliances reduces noise pollution in residential areas.

  2. TV and music systems must be run at low volume to reduce noise pollution.

  3. Planting of trees along the roads in residential areas adds to noise pollution as the leaves rustle in the wind.

  4. Noisy operations and noise producing industries should be set up away from residential areas to adhere noise levels laws.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plants cut down the sounds reaching the residents. Thus, they reduce the harmful effects of noise pollution.

Multiple choice

Sound waves which cannot be heard by the human ear is

  1. us sounds

  2. ultrasonic sounds

  3. inferior sounds

  4. jugular sounds

  5. polar sounds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ultrasonic sounds are frequencies above 20,000 Hz (20 kHz) that exceed human hearing range. These are used in medical imaging, cleaning, and navigation by animals like bats.

Multiple choice

The term 'AUDIO' is related to

  1. seeing

  2. hearing

  3. smelling

  4. feeling
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The term 'audio' is derived from Latin and relates to hearing or sound. It refers to technology or content related to sound reproduction and transmission. This is distinct from 'video' which relates to visual content, 'olfactory' for smell, or 'tactile' for touch.

Multiple choice

Sound travels faster in _________.

  1. sea water

  2. mercury

  3. kerosene

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sound travels fastest in denser media. Among the options, seawater (density ~1025 kg/m³) is the densest and sound travels at approximately 1530 m/s in seawater. Mercury is denser but sound doesn't propagate well in it due to high impedance. Kerosene is less dense than seawater.

Multiple choice

The quality of a tone

  1. decreases with loudness

  2. varies directly as pitch

  3. depends upon the overtones that are present there

  4. varies inversely as its frequency
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The quality of a tone depends upon the overtones that are present there.