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
  1. polarization

  2. diffraction

  3. refraction

  4. reflection

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

Polarization is a property specific to transverse waves, where the vibration occurs perpendicular to the direction of travel. Since sound waves in fluids like air are longitudinal, meaning they vibrate parallel to the direction of travel, they cannot be polarized. Light, being a transverse electromagnetic wave, does exhibit polarization.

Multiple choice
  1. a loud sound.

  2. a shrill sound.

  3. a flat sound.

  4. a sweet sound.

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

A mosquito's wings beat at a very high frequency, which produces a sound with a high pitch. In acoustics, high-pitched sounds are often described as shrill. This is distinct from loudness, which refers to the amplitude or volume of the sound.

Multiple choice
  1. natural vibration

  2. free vibration

  3. damped vibration

  4. forced vibration

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

Resonance occurs when a system is driven by an external periodic force at its natural frequency. This leads to a significant increase in the amplitude of oscillation. Because it requires an external driving force, it is classified as a specific case of forced vibration.

Multiple choice
  1. wavelength

  2. frequency

  3. amplitude

  4. periodicity and regularity

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

Pitch is the subjective perception of the frequency of a sound wave. Higher frequencies are perceived as higher pitches, while lower frequencies are perceived as lower pitches. Amplitude, by contrast, determines the loudness of the sound.

Multiple choice
  1. wavelength

  2. frequency

  3. amplitude

  4. overtone

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

Quality, or timbre, allows a listener to distinguish between two sounds that have the same pitch and loudness. It is determined by the specific combination and relative intensities of the overtones or harmonics present in the sound wave. This is why a piano and a violin sound different even when playing the same note.

Multiple choice
  1. a musical instrument

  2. a measure of sound level

  3. a musical noise

  4. the wavelength of noise

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

The decibel is a logarithmic unit used to express the ratio of two values of a physical quantity, typically power or intensity. In the context of acoustics, it is the standard unit used to measure sound pressure levels. It quantifies how loud a sound is perceived by the human ear.

Multiple choice
  1. lower than the original frequency.

  2. same as the original frequency.

  3. higher than the original frequency.

  4. lower or higher than the original frequency depending upon the speed of the source.

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

This phenomenon is known as the Doppler Effect. As a sound source moves toward a stationary observer, the sound waves are compressed in front of the source. This results in a higher frequency (and higher pitch) being perceived by the observer.

Multiple choice
  1. longitudinal stationary wave

  2. transverse progressive wave

  3. transverse stationary wave

  4. longitudinal progressive wave

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

Sound waves in air are longitudinal because the particles of the medium vibrate parallel to the direction of wave propagation. They are progressive because they transfer energy from the source (the sitar) to the listener. Stationary waves, by contrast, do not transfer energy across the medium.

Multiple choice
  1. decreases

  2. remains the same

  3. increases

  4. decreases and then increases

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

The speed of sound in a gas is proportional to the square root of its absolute temperature. As temperature increases, the kinetic energy of the gas molecules increases, allowing them to transmit the sound vibration more quickly. Therefore, sound travels faster on a hot day than on a cold day.

Multiple choice
  1. water

  2. air

  3. steel

  4. vacuum

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

Velocity of sound in a metallic solid will be higher than that in a gas or a liquid. Thus, velocity of sound is the greatest in steel.

Multiple choice
  1. speed

  2. frequency

  3. amplitude

  4. wavelength

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

Hertz is the SI unit of frequency, defined as one cycle per second. Speed, amplitude, and wavelength are physical properties that are measured in different units like m/s, meters, or decibels.

Multiple choice
  1. Speed

  2. Amplitude

  3. Wavelength

  4. Frequency

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

Hertz is the SI unit of frequency, defined as one cycle per second. Speed, amplitude, and wavelength have different units like meters per second, meters, or decibels.