Question 1

A piece of glass has a thin film of gasoline floating on it. A beam of light is shining perpendicular on the film. If the wavelength of light incident on the film is 560 nm and the indices of refraction of gasoline and glass are 1.40 and 1.50, respectively, what is the minimum nonzero thickness of the film to see a bright reflection?

Accepted Answer

A)   500 nm
B)   400 nm
C)   300 nm
D)   200 nm
E)   100 nmF) B) and D)
G) A) and B)

Question 2

Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 5.00 m. A person is standing 12.0 m away from the wall, equidistant from the loudspeakers. When the person moves 1.00 m parallel to the wall, she experiences destructive interference for the first time. What is the frequency of the sound? The speed of sound in air is 343 m/s.

Accepted Answer

A)   211 Hz
B)   256 Hz
C)   422 Hz
D)   512 Hz
E)   674 HzF) A) and C)
G) A) and B)

Question 3

Two motors in a factory are running at slightly different rates. One runs at 825 rpm and the other at 786 rpm. You hear the sound intensity increase and then decrease periodically due to wave interference. How much time elapses between successive maxima of the sound intensity?

Accepted Answer

A)   1.5 s
B)   1.4 s
C)   1.7 s
D)   1.8 sE) None of the above
F) All of the above

Question 4

A 1.30-m long gas column that is open at one end and closed at the other end has a fundamental resonant frequency 80.0 Hz. What is the speed of sound in this gas?

Accepted Answer

A)   104 m/s
B)   61.5 m/s
C)   26.0 m/s
D)   246 m/s
E)   416 m/sF) All of the above
G) B) and C)

Question 5

Two identical loudspeakers that are 5.00 m apart and face toward each other are driven in phase by the same oscillator at a frequency of 875 Hz. The speed of sound in the room is 344 m/s. If you start out standing midway between the speakers, find the shortest distance you can walk toward either speaker in order to hear a minimum of sound.

Accepted Answer

A)   0.0983 m
B)   0.197 m
C)   0.295 m
D)   0.393 m
E)   0.590 mF) A) and B)
G) A) and E)

Question 6

The sound from a single source can reach point O by two different paths. One path is 20.0 m long and the second path is 21.0 m long. The sound destructively interferes at point O. What is the minimum frequency of the source if the speed of sound is 340 m/s?

Accepted Answer

A)   340 Hz
B)   6800 Hz
C)   520 Hz
D)   680 Hz
E)   170 HzF) C) and D)
G) A) and E)

Question 7

In a resonating pipe that is open at both ends, there

Accepted Answer

A)   are displacement nodes at each end.
B)   are displacement antinodes at each end.
C)   is a displacement node at one end and a displacement antinode at the other end.
D)   None of the above are possible.E) A) and B)
F) A) and C)

Question 8

A string 40.0 cm long of mass 8.50 g is fixed at both ends and is under a tension of 425 N. When this string is vibrating in its third OVERTONE, you observe that it causes a nearby pipe, open at both ends, to resonate in its third HARMONIC. The speed of sound in the room is 344 m/s.
(a) How long is the pipe?
(b) What is the fundamental frequency of the pipe?

Accepted Answer

(a) 0.730 ...

Question 9

White light is incident normally on a thin soap film having an index of refraction of 1.34. It reflects with an interference maximum at 684 nm and an interference minimum at 570 nm with no minima between those two values. The film has air on both sides of it. What is the thickness of the soap film?

Accepted Answer

A)   766 nm
B)   627 nm
C)   638 nm
D)   894 nm
E)   510 nmF) B) and C)
G) None of the above

Question 10

A pipe is 0.90 m long and is open at one end but closed at the other end. If it resonates with a tone whose wavelength is 0.72 m, what is the wavelength of the next higher overtone in this pipe?

Accepted Answer

A)   0.36 m
B)   0.40 m
C)   0.45 m
D)   0.51 m
E)   0.58 mF) A) and D)
G) B) and C)

Question 11

The lowest-pitch tone to resonate in a pipe of length L that is closed at one end and open at the other end is 200 Hz. Which one of the following frequencies will NOT resonate in the same pipe?

Accepted Answer

A)   400 Hz
B)   600 Hz
C)   1000 Hz
D)   1400 Hz
E)   1800 HzF) A) and E)
G) D) and E)

Question 12

Two stereo speakers mounted 4.52 m apart on a wall emit identical in-phase sound waves. You are standing at the opposite wall of the room at a point directly between the two speakers. You walk 2.11 m parallel to the wall, to a location where you first notice that the sound intensity drops to zero. If the wall along which you are walking is 10.7 m from the wall with the speakers, what is the wavelength of the sound waves? CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers.

Accepted Answer

A)   1.7 m
B)   2.1 m
C)   2.6 m
D)   2.9 mE) None of the above
F) B) and C)

Question 13

A guitar string is fixed at both ends. If you tighten it to increase its tension

Accepted Answer

A)   the frequencies of its vibrational modes will increase but its wavelengths will not be affected.
B)   the wavelength increases but the frequency is not affected.
C)   both the frequency and the wavelength increase.D) A) and B)
E) None of the above A

Question 14

A tube open at one end and closed at the other end produces sound having a fundamental frequency of 350 Hz. If you now open the closed end, the fundamental frequency becomes

Accepted Answer

A)   87.5 Hz.
B)   175 Hz.
C)   350 Hz.
D)   700 Hz.
E)   1400 Hz.F) A) and E)
G) None of the above

Question 15

A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall. The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting. The speed of sound in air is 340 m/s. The speed of the bat is closest to

Accepted Answer

A)   20.0 m/s.
B)   530 m/s.
C)   10.0 m/s.
D)   30.0 m/s.
E)   5.02 m/s.F) B) and E)
G) A) and E) E

Question 16

A pipe that is 0.46 m long and open at both ends vibrates in the second overtone with a frequency of 1150 Hz. In this situation, the distance from the center of the pipe to the nearest antinode is closest to

Accepted Answer

A)   7.7 cm.
B)   3.8 cm.
C)   12 cm.
D)   15 cm.
E)   zero.F) None of the above
G) A) and B)

Question 17

A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wavelengths longer than these. This pipe is

Accepted Answer

A)   open at both ends.
B)   open at one end and closed at the other end.
C)   closed at both ends.
D)   We cannot tell because we do not know the frequency of the sound.E) All of the above
F) A) and C) B

Question 18

A 2.00-m long piano wire with a mass per unit length of 12.0 g/m is under a tension of 8.00 kN. What is the frequency of the fundamental mode of vibration of this wire?

Accepted Answer

A)   204 Hz
B)   102 Hz
C)   408 Hz
D)   510 Hz
E)   153 HzF) C) and E)
G) All of the above

Question 19

A soap bubble, when illuminated with light of frequency 5.11 × 1014 Hz, appears to be especially reflective. If it is surrounded by air and if its index of refraction is 1.35, what is the thinnest thickness the soap film can be? (c = 3.00 × 108 m/s)

Accepted Answer

Question 20

A coating is being applied to reduce the reflectivity of a pane of glass to light with a frequency of 5.75 × 1014 Hz that is incident normally on the pane. If the material has an index of refraction of 1.375 and the glass has an index of refraction of 1.537, what is the minimum thickness the coating should have? (c = 3.00 × 108 m/s)

Accepted Answer

A)   60.0 nm
B)   94.9 nm
C)   145 nm
D)   65.2 nm
E)   80.1 nmF) B) and C)
G) B) and E)

Exam 21: Superpositions

Correct Answer
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Correct Answer
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Two motors in a factory are running at slightly different rates. One runs at 825 rpm and the other at 786 rpm. You hear the sound intensity increase and then decrease periodically due to wave interference. How much time elapses between successive maxima of the sound intensity?

Correct Answer
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A 1.30-m long gas column that is open at one end and closed at the other end has a fundamental resonant frequency 80.0 Hz. What is the speed of sound in this gas?

Correct Answer
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Correct Answer
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The sound from a single source can reach point O by two different paths. One path is 20.0 m long and the second path is 21.0 m long. The sound destructively interferes at point O. What is the minimum frequency of the source if the speed of sound is 340 m/s?

Correct Answer
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In a resonating pipe that is open at both ends, there

Correct Answer
verified

Correct Answer
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(a) 0.730 ...
View Answer

White light is incident normally on a thin soap film having an index of refraction of 1.34. It reflects with an interference maximum at 684 nm and an interference minimum at 570 nm with no minima between those two values. The film has air on both sides of it. What is the thickness of the soap film?

Correct Answer
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A pipe is 0.90 m long and is open at one end but closed at the other end. If it resonates with a tone whose wavelength is 0.72 m, what is the wavelength of the next higher overtone in this pipe?

Correct Answer
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The lowest-pitch tone to resonate in a pipe of length L that is closed at one end and open at the other end is 200 Hz. Which one of the following frequencies will NOT resonate in the same pipe?

Correct Answer
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Correct Answer
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A guitar string is fixed at both ends. If you tighten it to increase its tension

Correct Answer
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A

A tube open at one end and closed at the other end produces sound having a fundamental frequency of 350 Hz. If you now open the closed end, the fundamental frequency becomes

Correct Answer
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A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall. The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting. The speed of sound in air is 340 m/s. The speed of the bat is closest to

Correct Answer
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E

A pipe that is 0.46 m long and open at both ends vibrates in the second overtone with a frequency of 1150 Hz. In this situation, the distance from the center of the pipe to the nearest antinode is closest to

Correct Answer
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A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wavelengths longer than these. This pipe is

Correct Answer
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B

A 2.00-m long piano wire with a mass per unit length of 12.0 g/m is under a tension of 8.00 kN. What is the frequency of the fundamental mode of vibration of this wire?

Correct Answer
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A soap bubble, when illuminated with light of frequency 5.11 × 10¹⁴ Hz, appears to be especially reflective. If it is surrounded by air and if its index of refraction is 1.35, what is the thinnest thickness the soap film can be? (c = 3.00 × 10⁸ m/s)

Correct Answer
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Correct Answer
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Exam 21: Superpositions

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Two motors in a factory are running at slightly different rates. One runs at 825 rpm and the other at 786 rpm. You hear the sound intensity increase and then decrease periodically due to wave interference. How much time elapses between successive maxima of the sound intensity?

Correct AnswerverifiedShow Answer

A 1.30-m long gas column that is open at one end and closed at the other end has a fundamental resonant frequency 80.0 Hz. What is the speed of sound in this gas?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The sound from a single source can reach point O by two different paths. One path is 20.0 m long and the second path is 21.0 m long. The sound destructively interferes at point O. What is the minimum frequency of the source if the speed of sound is 340 m/s?

Correct AnswerverifiedShow Answer

In a resonating pipe that is open at both ends, there

Correct AnswerverifiedShow Answer

Correct Answerverified(a) 0.730 ...View AnswerShow Answer

White light is incident normally on a thin soap film having an index of refraction of 1.34. It reflects with an interference maximum at 684 nm and an interference minimum at 570 nm with no minima between those two values. The film has air on both sides of it. What is the thickness of the soap film?

Correct AnswerverifiedShow Answer

A pipe is 0.90 m long and is open at one end but closed at the other end. If it resonates with a tone whose wavelength is 0.72 m, what is the wavelength of the next higher overtone in this pipe?

Correct AnswerverifiedShow Answer

The lowest-pitch tone to resonate in a pipe of length L that is closed at one end and open at the other end is 200 Hz. Which one of the following frequencies will NOT resonate in the same pipe?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A guitar string is fixed at both ends. If you tighten it to increase its tension

Correct AnswerverifiedA

A tube open at one end and closed at the other end produces sound having a fundamental frequency of 350 Hz. If you now open the closed end, the fundamental frequency becomes

Correct AnswerverifiedShow Answer

A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall. The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting. The speed of sound in air is 340 m/s. The speed of the bat is closest to

Correct AnswerverifiedE

A pipe that is 0.46 m long and open at both ends vibrates in the second overtone with a frequency of 1150 Hz. In this situation, the distance from the center of the pipe to the nearest antinode is closest to

Correct AnswerverifiedShow Answer

A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wavelengths longer than these. This pipe is

Correct AnswerverifiedB

A 2.00-m long piano wire with a mass per unit length of 12.0 g/m is under a tension of 8.00 kN. What is the frequency of the fundamental mode of vibration of this wire?

Correct AnswerverifiedShow Answer

A soap bubble, when illuminated with light of frequency 5.11 × 1014 Hz, appears to be especially reflective. If it is surrounded by air and if its index of refraction is 1.35, what is the thinnest thickness the soap film can be? (c = 3.00 × 108 m/s)

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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(a) 0.730 ...
View Answer

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Correct Answer
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A

Correct Answer
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Correct Answer
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E

Correct Answer
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Correct Answer
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B

Correct Answer
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A soap bubble, when illuminated with light of frequency 5.11 × 10¹⁴ Hz, appears to be especially reflective. If it is surrounded by air and if its index of refraction is 1.35, what is the thinnest thickness the soap film can be? (c = 3.00 × 10⁸ m/s)

Correct Answer
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Correct Answer
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