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

Consider the following statements:

  1. Supersonic Jet causes pollution by thinning of ozone layer.
  2. Infrasonic sound waves are used to clean clothes and fine machinery parts.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Statement 1 is correct. Supersonic Jet, flying at stratosphere heights, causes a major disturbance in the ozone levels. Statement 2 is incorrect. Ultrasonic (frequency greater than the upper limit of the human hearing range) sound waves are used to clean clothes and fine machinery parts.

Multiple choice

Consider the following statements:

  1. The velocity of sound in shallow water is more than the velocity in deep water.
  2. Ultrasonic waves are used in sonography.

Which of the given statements is/are incorrect?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Statement 1 is incorrect. The velocity of sound in deep water is more than the velocity in shallow water. Statement 2 is also correct. Ultrasonic waves are used in sonography.

Multiple choice

Consider the following statements:

  1. The walls of the halls built for musical concert should reflect the sound.
  2. Ultrasonic scanners are used to locate tumors in a tissue.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Statement 1 is incorrect. The walls of the halls built for musical concert should absorb the sound. If not, sound is reflected from walls, ceilings or floors which disturbs the sound from an orchestra or a speaker which reaches the audience. Statement 2 is correct. Scanners producing ultrasonic waves are used to locate the tumors in a tissue.

Multiple choice

Consider the following statements:

  1. Doppler principle is observed by both light and sound waves.
  2. Ear pinna receives the sound from external environment.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement 1 is correct. Doppler principle is the apparent change in frequency (and wavelength) of a wave that is perceived by an observer with respect to the change in the distance between the observer and the source. This principle is observed by both light and sound waves. Statement 2 is also correct. Ear pinna receives the sound from external environment. The pinna captures sounds in the environment and increases the loudness of those pitches that make it easier to understand speech.

Multiple choice

Which of the following statements are correct for sound? (1) Sound is produced whenever a body vibrates in a medium. (2) The speed of sound does not depend on the medium. (3) Sound is a form of energy. (4) The speed of sound is affected by the change in pressure.

  1. Only 1 and 2

  2. Only 1 and 3

  3. Only 1 and 4

  4. Only 2 and 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  1. Yes, whenever a body vibrates in a medium, sound will produce.
    1. The speed of sound depends on the medium. (Air < Liquid < Solid)
    2. Sound is a form of energy because energy always carried sound waves.
    3. The speed of sound is independent of pressure.
Multiple choice

Consider the following statements:

  1. Dolphins detect their enemy and obstacles by emitting the supersonic waves and hearing their echo.
  2. Resonance of sound is observed in radio and TV receivers.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Statement 1 is incorrect. Dolphins detect their enemy and obstacles by emitting the ultrasonic waves and hearing their echo. Solution 2 is correct. The tuning of radio and TV receivers is based on resonance. Radio and TV receivers have electronic circuits which produce vibrations of the different frequencies.

Multiple choice

Consider the following statements:

  1. Guitar is played by forced vibrations.
  2. Loudness of a sound does not depend on the density of medium.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Statement 1 is correct. When a guitar is played, the artist forces the strings of the guitar to execute forced vibrations. Statement 2 is incorrect. Loudness of a sound depends on the density of medium. More the density of medium, more is the loudness.

Multiple choice

Consider the following statements:

  1. Ultrasonic waves are utilised for monitoring earthquakes, charting rock and petroleum formations below the earth.
  2. Above 80 dB, the sound produced is regarded as noise pollution.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statement 1 is incorrect. Infrasonic sound waves are utilised for monitoring earthquakes, charting rock and petroleum formation below the earth. Statement 2 is also incorrect. Above 120 dB, the sound produced is regarded as noise pollution. The audible range of humans is 0dB - 120dB

Multiple choice

Match the following:

 
1. Pitch (i) Hearing of sound after reflection
2. Echo (ii) Sensation perceived by the listener
3. Doppler effect (iii) Difference in two sounds of the same loudness
4. Quality (Timbre) (iv) Change in frequency of sound with respect to body position

  1. 1 - (ii), 2 - (i), 3 - (iv), 4 - (iii)

  2. 1 - (iii), 2 - (i), 3 - (iv), 4 - (ii)

  3. 1 - (ii), 2 - (iv), 3 - (iii), 4 - (i)

  4. 1 - (iii), 2 - (ii), 3 - (iv), 4 - (i)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  1. Pitch - (ii) Sensation perceived by the listener
    1. Echo - (i) Hearing of sound after reflection
    2. Doppler effect - (iv) Change in frequency of sound with respect to body position
    3. Quality (Timbre) - (iii) Difference in two sounds of the same loudness
Multiple choice

Consider the following statements:

  1. The US Department of Defense (DOD) has acoustic weapons that use sound to injure, incapacitate or kill an opponent.
  2. The intensity of sound increases at night.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement 1 is correct. The US Department of Defense (DOD) has acoustic weapons that use sound to injure, incapacitate or kill an opponent. Statement 2 is also correct. The intensity of sound increases at night due to increase in density of air.

Multiple choice

Consider the following statements:

  1. Larynx is responsible for the voice in humans.
  2. Microphone produces sound by vibrations of its diaphragm.

Which of the given statements is/are correct?

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement 1 is correct. Larynx is responsible for the voice in humans. Therefore it is also called voicebox. Statement 2 is also correct. The sound falls on the diaphragm of the microphone and produces vibrations of high frequency.