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

The loudness of sound is determined by its

  1. frequency

  2. wavelength

  3. amplitude

  4. resonance
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Loudness of sound is determined by its amplitude - the greater the amplitude of vibration, the louder the sound. Frequency determines pitch, wavelength is the distance between wave crests, and resonance is a phenomenon that amplifies sound but doesn't determine loudness.

Multiple choice

Which of the following is known as Mach number?

  1. It is the ratio of speed of an object moving through a fluid to the local speed of sound in that fluid.

  2. It is the range of audibility.

  3. It is the range of soothing sound measured in dB.

  4. Sounds with frequencies more than 20,000 Hz are called ultrasonic waves.

  5. It is the speed of sound in air at 0oC.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 It is the ratio of speed of an object moving through a fluid to the local speed of sound in that fluid.

Multiple choice

Which of the following statements are correct for sound? (a) Sound is produced whenever a body vibrates in a medium. (b) The speed of sound does not depend on the elasticity of the medium. (c) They are called as mechanical waves. (d) The speed of sound is not affected by the change in pressure.

  1. Both (a) and (b)

  2. Both (a) and (c)

  3. Both (b) and (c)

  4. Both (b) and (d)

  5. Both (a) and (d)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sound is produced whenever a body vibrates in a medium. They are called as mechanical waves.

Multiple choice

We can hear sound when a body is in a _____ state.

  1. vibrating

  2. solid

  3. liquid

  4. gaseous
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sound is produced when a body vibrates, creating compression and rarefaction in the surrounding medium. The vibrating body disturbs the medium particles, which then carry the sound energy. Without vibration, no sound can be produced.

Multiple choice

Which of the following correctly defines the intensity of sound?

  1. It is defined as number of vibrations per second.

  2. It is defined as one complete cycle of the periodic motion of the particle of the medium.

  3. It is defined as the maximum displacement of a particle of vibrating body producing sound.

  4. It is defined as the amount of sound energy passing per second through unit area.

  5. It is defined as the distance between two consecutive compressions or rarefactions.

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Intensity is defined as the amount of sound energy passing per second through unit area.

Multiple choice

Which of the following is not a use of ultrasonic sound?

  1. To repel mosquitoes and other insects

  2. To scan and get images of inner body parts

  3. To detect cracks in metal blocks

  4. Drum beats for mass drill in a school

  5. In sonars used in ships
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Drum beats for mass drill in a school must be heard by all students. So, it is in the audible frequency range.

Multiple choice

Which of the following statements about sound is incorrect?

  1. Sound needs a medium to travel.

  2. Speed of sound is fastest in gases and slowest in solids.

  3. Sound of frequency below the audible range is called infrasonic sound.

  4. Excessive sound in the environment causes noise pollution.

  5. Sound is produced by vibrating objects.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Speed of sound is fastest in solids and slowest in gases.