Chapter 20

Sound

The sound waves that most humans cannot hear are

a. infrasonic.

b. ultrasonic.

c. Both of these.

d. None of the above, for young people can hear both.

The sound waves that most humans cannot hear are

a. infrasonic.

b. ultrasonic.

c. Both of these.

d. None of the above, for young people can hear both.

Sound travels in air by a series of

a. compressions.

b. rarefactions.

c. Both of these.

d. None of these.

Sound travels in air by a series of

a. compressions.

b. rarefactions.

c. Both of these.

d. None of these.

The vibrations set up in a radio loudspeaker have the same frequencies

as the vibrations

a. in the electric signal feeding the loudspeaker.

b. that produce the sound you hear.

c. Both of these.

d. None of these.

The vibrations set up in a radio loudspeaker have the same frequencies

as the vibrations

a. in the electric signal feeding the loudspeaker.

b. that produce the sound you hear.

c. Both of these.

d. None of these.

Sound travels in

a. solids.

b. liquids.

c. gases.

d. All of these.

Sound travels in

a. solids.

b. liquids.

c. gases.

d. All of these.

In which of these materials does sound travel fastest?

a. Air

b. Water

c. Steel

d. All the same at the same temperature

In which of these materials does sound travel fastest?

a. Air

b. Water

c. Steel

d. All the same at the same temperature

The speed of sound varies with

a. amplitude.

b. frequency.

c. temperature.

d. All of these.

The speed of sound varies with

a. amplitude.

b. frequency.

c. temperature.

d. All of these.

Explanation: Although loudness varies with amplitude, and pitch varies with frequency, speed is not influenced by amplitude nor frequency. A listener in the back row at a concert would find music confusing if sound of different frequencies reached the ear at different times.

The loudness of a sound is most closely related to its

a. frequency.

b. period.

c. wavelength.

d. amplitude.

The loudness of a sound is most closely related to its

a. frequency.

b. period.

c. wavelength.

d. amplitude.

Sound made to undergo reverberation is sound that is

a. sympathetically vibrating.

b. varying in tone.

c. multiply reflected.

d. refracted.

Sound made to undergo reverberation is sound that is

a. sympathetically vibrating.

b. varying in tone.

c. multiply reflected.

d. refracted.

When sound undergoes refraction, it undergoes a change in

a. frequency.

b. wavelength.

c. speed.

d. intensity.

When sound undergoes refraction, it undergoes a change in

a. frequency.

b. wavelength.

c. speed.

d. intensity.

Sound can NOT be

a. reflected.

b. absorbed.

c. diminished by interference.

d. None of these.

Sound can NOT be

a. reflected.

b. absorbed.

c. diminished by interference.

d. None of these.

Comment: Sound, like any wave, can undergo all of these!

Sensing an invisible object by way of ultrasound is used by

a. bats.

b. dolphins

c. medical doctors.

d. All of these.

Sensing an invisible object by way of ultrasound is used by

a. bats.

b. dolphins

c. medical doctors.

d. All of these.

Sound normally travels farther in air when the sound is

a. low frequency.

b. high frequency.

c. resonant.

d. low in energy.

Sound normally travels farther in air when the sound is

a. low frequency.

b. high frequency.

c. resonant.

d. low in energy.

Explanation: Hence the low tone of fog horns.

A factory floor vibrates, and as a result you vibrate when standing on the floor.

This is

a. forced vibration.

b. resonance.

c. refraction.

d. diffraction.

A factory floor vibrates, and as a result you vibrate when standing on the floor.

This is

a. forced vibration.

b. resonance.

c. refraction.

d. diffraction.

When you tap various objects, they produce characteristic sounds that are

related to

a. wavelength.

b. amplitude.

c. period.

d. natural frequency.

When you tap various objects, they produce characteristic sounds that are

related to

a. wavelength.

b. amplitude.

c. period.

d. natural frequency.

When the surface of a guitar is made to vibrate, we say it undergoes

a. forced vibration.

b. resonance.

c. refraction.

d. amplitude enhancement.

When the surface of a guitar is made to vibrate, we say it undergoes

a. forced vibration.

b. resonance.

c. refraction.

d. amplitude enhancement.

Comment: The sound may be enhanced, but it is the surface of the guitar that undergoes forced vibration.

When an object is set vibrating by a wave having a frequency that matches

the natural frequency of the object, what occurs is

a. forced vibration.

b. resonance.

c. refraction.

d. amplitude enhancement.

When an object is set vibrating by a wave having a frequency that matches

the natural frequency of the object, what occurs is

a. forced vibration.

b. resonance.

c. refraction.

d. amplitude enhancement.

Comment: Resonance, rather than amplitude enhancement, is the better answer.

Noise-canceling devices such as jackhammer earphones make use of

sound

a. destruction.

b. interference.

c. resonance.

d. amplification.

Noise-canceling devices such as jackhammer earphones make use of

sound

a. destruction.

b. interference.

c. resonance.

d. amplification.

The phenomenon of beats is the result of sound

a. destruction.

b. interference.

c. resonance.

d. amplification.

The phenomenon of beats is the result of sound

a. destruction.

b. interference.

c. resonance.

d. amplification.

When a 134-Hz tuning fork and a 144-Hz tuning fork are struck, the

beat frequency is

a. 2 Hz.

b. 6 Hz.

c. 8 Hz.

d. more than 8 Hz.

When a 134-Hz tuning fork and a 144-Hz tuning fork are struck, the

beat frequency is

a. 2 Hz.

b. 6 Hz.

c. 8 Hz.

d. more than 8 Hz.

Explanation: The beat frequency is the difference between the two, 10 Hz (which is more than 8 Hz).

When your radio set is tuned to an incoming radio signal, what occurs?

a. Forced vibration

b. Resonance

c. Refraction

d. Diffraction

When your radio set is tuned to an incoming radio signal, what occurs?

a. Forced vibration

b. Resonance

c. Refraction

d. Diffraction