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

Frequency of sound below 20 Hz is called

  1. sonar

  2. ultrasounds

  3. infrasonic sounds

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

Sound waves with frequencies below the human audible range of 20 Hz are classified as infrasonic. Ultrasound refers to frequencies above 20,000 Hz.

Multiple choice

Sound is a form of

  1. matter

  2. energy

  3. smell

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

Sound is a mechanical wave that propagates through a medium by transferring energy from one particle to another. It is not matter, as it does not have mass or occupy space.

Multiple choice

When returning to the earth, spacecrafts have a communication blackout, the reason for this is

  1. the returning spacecraft is doing so against the force of gravity which interferes with the radio waves

  2. during the re-entry period the density of the plasma generated by the intense frictional heat is so high that the operational, frequencies used for communication become less than the plasma cut-off frequency resulting a total blackout

  3. stellar X-rays attract and absorb the sound waves

  4. the sounds created by the whirring of the mechanism of the spacecraft renders the sounds inaudible
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During re-entry, the spacecraft creates a layer of ionized gas (plasma) due to extreme friction. This plasma layer blocks radio waves, causing a temporary communication blackout.

Multiple choice

Echo is produced due to ------

  1. absorption of sound

  2. reflection of sound

  3. dispersion of sound

  4. refraction of sound

  5. none
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An echo is a reflection of sound that arrives at the listener with a delay after the direct sound.

Multiple choice

Which of the following waves is related to Acoustic Radar?

  1. Longitudinal waves

  2. Electromagnetic waves

  3. Elastic waves

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

Acoustic radar, also known as SODAR (Sonic Detection and Ranging), relies on the reflection of sound waves. Sound waves are a type of elastic wave that requires a medium to propagate.

Multiple choice

Sound cannot travel through

  1. solids

  2. water

  3. vacuum

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

Sound is a longitudinal wave which requires a medium to travel. Hence, it cannot travel through vacuum.

Multiple choice

Sound is produced by

  1. vibration

  2. moving

  3. heating

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

Sound is produced and propagated by vibrations.

Multiple choice

Loudness of sound depends upon its

  1. Wavelength

  2. Frequency

  3. Time period

  4. Amplitude
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Loudness is the measure of intensity of sound which in turn depends on the amplitude.