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
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polarization
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diffraction
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refraction
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reflection
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.
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a loud sound.
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a shrill sound.
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a flat sound.
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a sweet sound.
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.
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natural vibration
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free vibration
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damped vibration
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forced vibration
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.
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wavelength
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frequency
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amplitude
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periodicity and regularity
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.
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wavelength
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frequency
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amplitude
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overtone
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.
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a musical instrument
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a measure of sound level
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a musical noise
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the wavelength of noise
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.
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lower than the original frequency.
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same as the original frequency.
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higher than the original frequency.
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lower or higher than the original frequency depending upon the speed of the source.
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.
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longitudinal stationary wave
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transverse progressive wave
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transverse stationary wave
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longitudinal progressive wave
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.
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sonics
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infrsonics
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ultrasonics
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supersonics
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decreases
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remains the same
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increases
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decreases and then increases
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.
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.
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Doppler's law
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Huygen's law
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Newton's law
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Galileo's law
A
Correct answer
Explanation
The law applicable for determining the apparent change in frequency when a source and an observer are in motion is Doppler's law.
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speed
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frequency
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amplitude
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wavelength
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.
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Speed
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Amplitude
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Wavelength
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Frequency
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.
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Sound wave
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Microwave
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Light wave
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Ocean wave
A
Correct answer
Explanation
Sound waves are longitudinal waves, meaning the displacement of the medium is parallel to the direction of wave propagation. Light, microwave, and ocean waves are transverse.