Question 1

Suppose an audible sound wave were being produced at a frequency of 800 cycles per second. If the frequency were doubled, the sound would become
A) softer.
B) louder.
C) lower in pitch.
D) higher in pitch.

Accepted Answer

Doubling the frequency of an audible sound wave would result in a higher pitch. The pitch of a sound wave is directly proportional to its frequency, so an increase in frequency would lead to an increase in pitch.

Question 2

You hear a musician playing a series of notes of increasing frequency. As the frequency increases, the wave speed
A) increases.
B) decreases.
C) stays the same.

Accepted Answer

The wave speed depends on the medium through which the wave is traveling and does not change with frequency. Therefore, as the musician plays notes of increasing frequency, the wave speed will stay the same.

Question 3

When a wave reflects from a stationary boundary,
A) the frequency increases.
B) the frequency decreases.
C) the frequency is unchanged.

Accepted Answer

When a wave reflects from a stationary boundary, the frequency remains unchanged. The only thing that changes is the direction of the wave propagation.

Question 4

Which of the following is a longitudinal wave?
A) a sound wave in a gas
B) a wave on string under tension
C) a light wave
D) All of these choices are correct.
E) None of these choices is correct.

Accepted Answer

A sound wave in a gas is an example of a longitudinal wave, where the particles in the medium vibrate parallel to the direction of wave propagation. Waves on a string under tension are transverse waves, where particles in the medium vibrate perpendicular to the direction of wave propagation. Light waves are also transverse waves. Therefore, options B and C are not longitudinal waves.

Question 5

The principle of superposition tells us that, if two waves cross paths,
A) the amplitude is the sum of the individual amplitudes.
B) the wavelength is the sum of the individual wavelengths.
C) the frequency is the sum of the individual frequencies.
D) the speed is the speed of the faster wave.

Accepted Answer

The principle of superposition states that when two waves cross paths, the resulting wave is the sum of the individual waves. This means that the amplitude of the resulting wave is the sum of the individual amplitudes of the two waves.

Question 6

On a day when the speed of sound in air is 340 m/s, a lightning bolt is observed and the resultant thunderclap is heard 5 seconds afterwards. About how far away was the lightning bolt?
A) 1020 m
B) 170 m
C) 1700 m
D) 680 m

Accepted Answer

The distance (d) can be calculated using the formula:
d = speed × time
In this case, the speed is the speed of sound in air, which is 340 m/s, and the time is 5 seconds.
So, 
d = 340 m/s × 5 s
d = 1700 meters 
Therefore, the lightning bolt was about 1700 meters away from the observer.

Question 7

If the speed of sound is 1100 feet per second and a tuning fork oscillates at 440 cycles per second, what is the wavelength $\lambda$ of the sound produced?
A) 0.4 foot
B) 2.5 feet
C) 4.4 feet
D) 11 feet

Accepted Answer

The formula for wavelength is:
wavelength = speed of sound / frequency

Substituting the given values, we get:
wavelength = 1100 / 440
wavelength = 2.5 feet

Therefore, the correct answer is B.

Question 8

A musical tone is coming from a loudspeaker. If a second loudspeaker nearby were to start playing exactly the same tone, the sound would
A) get louder everywhere.
B) get softer everywhere.
C) stay the same everywhere.
D) get louder in some areas and get softer in others.

Accepted Answer

When two loudspeakers play exactly the same tone, the sound waves they produce will interfere with each other. In some areas, the waves will constructively interfere, making the sound louder, and in other areas, they will destructively interfere, making the sound softer. This phenomenon is known as interference.

Question 9

Which of these lists is in order of increasing wavelength?
A) Second harmonic, third harmonic, fourth harmonic
B) First harmonic, second harmonic, fundamental
C) Third harmonic, second harmonic, first harmonic
D) First harmonic, second harmonic, third harmonic

Accepted Answer

The wavelength of a harmonic is inversely proportional to the harmonic number (n). Therefore, as the harmonic number increases, the wavelength decreases. In option C, the third harmonic has the shortest wavelength (highest frequency), followed by the second harmonic and then the first harmonic (lowest frequency).

Question 10

The Doppler effect refers to changes in a sound wave's
A) frequency caused by motion of a source or receiver.
B) frequency caused by a change in speed of sound.
C) amplitude caused by motion of a source or receiver.
D) amplitude caused by a change in speed of sound.

Accepted Answer

The Doppler effect refers to changes in frequency caused by motion of a source or receiver. It is the reason why a siren sounds higher-pitched when the ambulance is approaching and lower-pitched when it is moving away. The Doppler effect has nothing to do with changes in amplitude caused by motion or changes in the speed of sound.

Question 11

To change the fundamental frequency of a guitar string, you can
A) use something other than a pick.
B) strum it over the sound hole.
C) do nothing short of using a completely different guitar.
D) make it shorter, by pressing a finger of your left hand on the string.

Accepted Answer

By pressing a finger of your left hand on the string, you change the effective length of the string and therefore change its fundamental frequency. This is commonly done when playing different notes on the guitar. The other choices are not effective ways to change the fundamental frequency of a guitar string.

Question 12

The pitch of a sound is determined primarily by its
A) frequency.
B) speed.
C) duration.
D) amplitude.

Accepted Answer

The pitch of a sound is determined primarily by its frequency, which is the number of vibrations or cycles per second that the sound wave completes. The higher the frequency, the higher the pitch of the sound.

Question 13

The period and the frequency of a sound wave are
A) independent of each other.
B) multiples of each other-period is 2$\pi$ times the frequency.
C) reciprocals of each other.
D) none of these.

Accepted Answer

The period and the frequency of a sound wave are reciprocals of each other. The period is the duration of one cycle of a wave, while the frequency is the number of cycles per second.

Question 14

Jim the meteorologist has predicted fair weather all day but sees flashes of lightning followed by rolls of thunder. To calculate the distance to the lightning bolt, Jim should measure the time between the instant he first sees a lightning flash and the
A) instant the lightning flash is over.
B) instant he hears the beginning of the next thunder roll.
C) instant he hears the middle of the next thunder roll.
D) instant he hears the end of the next thunder roll.
E) instant he sees the beginning of the next lightning flash.

Accepted Answer

This is because the time it takes for sound to travel from thunder to the observer is much slower than the speed of light, so there will be a delay between seeing the lightning and hearing the thunder. By timing the delay between seeing the lightning flash and hearing the beginning of the next thunder roll, Jim can calculate the distance to the lightning bolt using the speed of sound.

Question 15

A guitar is perfectly tuned. The tension on its strings is then increased. Which of the following is true?
A) The frequencies of sounds from the guitar are higher than before.
B) The wavelengths of sounds from the guitar are longer than before.
C) The speed of sounds from the guitar is larger than before.
D) The amplitudes of sounds from the guitar are larger.

Accepted Answer

Increasing tension on the strings of a guitar results in an increase in frequency, causing the sounds produced to be higher. This is because the frequency of a sound wave is directly proportional to the tension in the string. Additionally, this increase in tension will also increase the speed of sound in the strings, as well as the amplitude of the sounds produced to a certain degree. However, the wavelength of the sound waves will decrease, as the speed of sound increases while the frequency remains constant.

Question 16

As a wave passes from one medium into another, it often happens that its speed increases with no change in frequency. Under these circumstances, the wavelength
A) increases.
B) decreases.
C) stays the same.

Accepted Answer

When a wave's speed increases as it passes from one medium to another without a change in frequency, its wavelength increases. This is because wavelength is directly proportional to the wave's speed when the frequency remains constant (wavelength = speed/frequency).

Question 17

Suppose an audible sound wave were being produced at a frequency of 800 cycles per second. If the amplitude were doubled, the sound would become
A) louder.
B) softer.
C) higher in pitch.
D) lower in pitch.

Accepted Answer

Doubling the amplitude of a sound wave increases its intensity, making it louder. Changing the amplitude does not affect the frequency (pitch) of the sound wave.

Question 18

Electromagnetic waves are generally
A) longitudinal waves.
B) transverse waves.
C) a 50/50 combination of transverse and longitudinal waves.
D) standing waves.

Accepted Answer

Electromagnetic waves are transverse waves, meaning that the oscillations of the wave are perpendicular to the direction of its propagation.

Question 19

Imagine you are holding a long rope under tension attached to a distant support. You can generate periodic waves by shaking the end up and down. Changing which of the following will least affect the velocity of waves along the string?
A) tension
B) mass per unit length of rope
C) frequency
D) None of these affect the wave speed.

Accepted Answer

The velocity of waves on a string is determined by the tension in the string and the mass per unit length of the string, according to the formula $v = \sqrt{\frac{T}{\mu}}$, where $v$ is the velocity, $T$ is the tension, and $\mu$ is the mass per unit length. The frequency of the waves you generate by shaking the rope does not directly affect the velocity of the waves; it affects the wavelength instead.

Question 20

When a wave crosses from one medium into another in which the wave speed is lower, the frequency is unchanged. The wavelength
A) increases.
B) decreases.
C) stays the same.

Accepted Answer

When a wave crosses into a medium where the speed is lower, while its frequency remains unchanged, its wavelength decreases to maintain the wave speed equation v = fλ, where v is speed, f is frequency, and λ is wavelength.

Quiz 15: Making Waves

Suppose an audible sound wave were being produced at a frequency of 800 cycles per second. If the frequency were doubled, the sound would become

You hear a musician playing a series of notes of increasing frequency. As the frequency increases, the wave speed

When a wave reflects from a stationary boundary,

Which of the following is a longitudinal wave?

The principle of superposition tells us that, if two waves cross paths,

On a day when the speed of sound in air is 340 m/s, a lightning bolt is observed and the resultant thunderclap is heard 5 seconds afterwards. About how far away was the lightning bolt?

If the speed of sound is 1100 feet per second and a tuning fork oscillates at 440 cycles per second, what is the wavelength λ\lambdaλ of the sound produced?

A musical tone is coming from a loudspeaker. If a second loudspeaker nearby were to start playing exactly the same tone, the sound would

Which of these lists is in order of increasing wavelength?

The Doppler effect refers to changes in a sound wave's

To change the fundamental frequency of a guitar string, you can

The pitch of a sound is determined primarily by its

The period and the frequency of a sound wave are

Jim the meteorologist has predicted fair weather all day but sees flashes of lightning followed by rolls of thunder. To calculate the distance to the lightning bolt, Jim should measure the time between the instant he first sees a lightning flash and the

A guitar is perfectly tuned. The tension on its strings is then increased. Which of the following is true?

As a wave passes from one medium into another, it often happens that its speed increases with no change in frequency. Under these circumstances, the wavelength

Suppose an audible sound wave were being produced at a frequency of 800 cycles per second. If the amplitude were doubled, the sound would become

Electromagnetic waves are generally

Imagine you are holding a long rope under tension attached to a distant support. You can generate periodic waves by shaking the end up and down. Changing which of the following will least affect the velocity of waves along the string?

When a wave crosses from one medium into another in which the wave speed is lower, the frequency is unchanged. The wavelength

If the speed of sound is 1100 feet per second and a tuning fork oscillates at 440 cycles per second, what is the wavelength $\lambda$ of the sound produced?