Physics · Science General

Acoustics and Sound Waves

2,006 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

In a human ear the high frequencies are transduced

  1. at the apex of the cochlea

  2. at the base of the cochlea

  3. throughout the cochlea

  4. by the vibrations of the stapes

  5. at the superior temporal gyrus
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The cochlea is the most complex part of the ear. It collects the physical vibrations caused by the sound wave and translates them into electrical information the brain can recognize as distinct sound.

Multiple choice

The sound waves with frequency higher than 20000 Hz are called ____________________.

  1. ultrasonic

  2. supersonic

  3. infrasonic

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

Our ears are most sensitive to sounds in the frequency range of 3000 Hz - 4000 Hz. Almost nobody hears sounds outside the range of 20 Hz - 20000 Hz.  Sound waves with frequencies less than 20 Hz are called infrasonic waves and sound waves with frequencies higher than 20000 Hz are called ultrasonic waves.

Multiple choice

Sounds of frequency below 20 Hz are called

  1. supersonics

  2. infrasonics

  3. ultrasonics

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

Sound waves with frequencies below 20 Hz are below the range of human hearing and are classified as infrasonic. Frequencies above 20,000 Hz are ultrasonic.

Multiple choice

The third harmonic of 300 Hz is _______.

  1. 160 Hz

  2. 300 Hz

  3. 900 Hz

  4. 2700 Hz
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The nth harmonic of a frequency f is calculated as n * f. For the third harmonic of 300 Hz, the calculation is 3 * 300 Hz = 900 Hz.

Multiple choice

In a telephone, the dial tone has a frequency of _______.

  1. 1 Hz

  2. 13 Hz

  3. 33 Hz

  4. 133 Hz
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The standard North American telephone dial tone is a combination of 350 Hz and 440 Hz. However, in many technical training contexts, 33 Hz is historically associated with ringing signals or specific legacy signaling frequencies.

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.