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Course: American System Physics
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American System Physics

A Physics Toolkit

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Representing Motion

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Accelerated Motion

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Forces in One Dimension

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Displacement and Force in Two Dimensions

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Motion in Two Dimensions

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Gravitation

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Rotational Motion

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Momentum and Its Conservation

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Energy and Its Conservation

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Thermal Energy

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States of Matter

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Vibrations and Waves

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Sound

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Fundamentals of Light

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Reflection and Refraction

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Interference and Diffraction

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Electrostatics

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Electric Current and Circuits

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Magnetic Fields

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Electromagnetic Induction and Electromagnetism

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Quantum Theory and the Atom

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Solid-State Electronics

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Nuclear and Particle Physics

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Quiz

14.1 Properties and Detection of Sound – Quiz

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Properties and Detection of Sound American Physics quiz: free practice for American System Physics. Work through this Properties and Detection of Sound American Physics quiz and get instant feedback on every answer. If you get stuck, review the 14.1 Properties and Detection of Sound — Notes lesson. More practice: American System Physics — all units. Syllabus: OpenStax free science textbooks.

  • Questions count: 50
  • Passing grade: A-
  • Time limit:
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1.
The oscilloscope shows two sound traces recorded with the same settings: the solid trace and the dashed trace B. How does the solid-trace sound compare with sound B?
Dr Dabour Hub Academy - figure 1
Higher pitch and louder
Lower pitch and louder
Higher pitch and quieter
Same pitch and louder
2.
A microphone connected to an oscilloscope gives the trace shown. The time-base is set to 0.20 ms/div. What is the frequency of the sound?
Dr Dabour Hub Academy - figure 2
5000 Hz
1000 Hz
500 Hz
2000 Hz
3.
The diagram shows wavefronts from a siren S moving to the right. Which observer hears the higher pitch, and why?
Dr Dabour Hub Academy - figure 3
Y, because wavefronts are spread out behind the source
X, because the sound travels faster in front of the source
X, because wavefronts are bunched up in front of the source, giving a shorter wavelength
Both hear the same pitch because the siren frequency is fixed
4.
A ship's sonar display shows the transmitted pulse and its echo from the seabed. Sound travels at 1500 m/s in seawater. How deep is the seabed?
Dr Dabour Hub Academy - figure 4
18 m
36 m
9.0 m
18000 m
5.
The snapshot shows the displacement of air particles along the path of a sound wave. The speed of sound is 340 m/s. What is the frequency?
Dr Dabour Hub Academy - figure 5
231 Hz
500 Hz
1000 Hz
200 Hz
6.
The graph shows how the displacement of one air particle varies with time as a note is played. What is the frequency of the note?
Dr Dabour Hub Academy - figure 6
0.400 Hz
250 Hz
400 Hz
200 Hz
7.
A signal from a probe is displayed on the oscilloscope shown with a time-base of 20 µs/div. Could a human hear this sound?
Dr Dabour Hub Academy - figure 7
Yes: its frequency is 25 Hz, within the audible range
Yes: its frequency is 2.5 kHz
No: its frequency is 12 Hz, which is infrasound
No: its frequency is 25 kHz, which is ultrasound
8.
A student claps once in front of a cliff and a microphone records the signal shown. The speed of sound is 340 m/s. How far away is the cliff?
Dr Dabour Hub Academy - figure 8
102 m
204 m
51.0 m
567 m
9.
The oscilloscope shows the sound from a tuning fork before (solid) and after (dashed B) it is struck harder. What has changed?
Dr Dabour Hub Academy - figure 9
The frequency has increased, so the pitch is higher
The amplitude has increased, so the sound is louder, but the pitch is the same
Both pitch and loudness have increased
The speed of the sound has increased
10.
Two observers 150 m apart measure the time between seeing and hearing two blocks bang together (table). What is the speed of sound?
66.0 m/s
357 m/s
341 m/s
682 m/s
11.
A student claps in rhythm with the echo from a wall and records the results in the table. What value do they obtain for the speed of sound?
169 m/s
16.9 m/s
29.5 m/s
339 m/s
12.
A hammer strikes one end of a 1180 m steel rail. Using the table, how much sooner does the sound arrive through the steel than through the air?
3.24 s
3.44 s
0.200 s
0.787 s
13.
Using the table, how many times more intense is the sound at a rock concert than normal conversation?
50 times
100 000 times
1.8 times
500 times
14.
The table shows the speed of sound in air at different temperatures. What is the likely speed at 30 °C?
343 m/s
361 m/s
349 m/s
331 m/s
15.
Which sound in the table is infrasound?
Dog whistle
Human speech
Piano top note
Elephant rumble
16.
A car horn of 600 Hz moves at 20 m/s past a stationary listener (speed of sound 343 m/s). Complete the table: what frequency is heard while it approaches?
637 Hz
567 Hz
600 Hz
565 Hz
17.
The table shows sound intensity at distances from a small speaker. What intensity is expected at 4.0 m?
10 mW/m²
5.0 mW/m²
40 mW/m²
2.5 mW/m²
18.
An electric bell rings inside a jar as the air is pumped out (table). What does the experiment show?
Sound travels faster when air is removed
The bell stops vibrating as air is removed
Sound needs a medium to travel, but light does not
Light needs air to travel
19.
In the two-observer method for measuring the speed of sound, why does the timer start the stopwatch on seeing the blocks bang together?
Sound and light arrive together
It removes all reaction-time error
The sound is too quiet to hear at the start
Light arrives almost instantly, so seeing the action marks when the sound was made
20.
Why must the two observers be at least 100 m apart when measuring the speed of sound?
So the travel time is long compared with reaction time, reducing the percentage error
So the sound is loud enough
Because sound travels only in straight lines over long distances
To stop echoes from happening
21.
What instrument is best for measuring the 150 m distance between the observers in an open field?
30 cm ruler
Trundle wheel
Vernier callipers
Stopwatch
22.
A student wants a more accurate electronic measurement of the speed of sound over 2.0 m on a bench. Which method is best?
Two microphones 2.0 m apart connected to a fast timer that starts and stops as the sound passes each one
A stopwatch started when a clap is heard and stopped at the far end
Measuring the loudness at each end with a sound meter
Counting echoes from the lab wall by ear
23.
A sound of frequency 850 Hz travels in air at 340 m/s. What is its wavelength?
2.5 m
0.40 m
289000 m
1.2 m
24.
An ultrasound pulse sent into a steel block returns from a crack after 0.020 ms. Sound travels at 5900 m/s in steel. How deep is the crack?
0.12 m
59 m
0.059 m
0.030 m
25.
A police car with a 900 Hz siren drives away from a stationary listener at 30 m/s. The speed of sound is 343 m/s. What frequency does the listener hear?
828 Hz
986 Hz
900 Hz
78.7 Hz
26.
A sound level rises from 40 dB to 60 dB. By what factor has the intensity increased?
20
100
1.5
2
27.
Why does sound travel faster in steel than in air?
Steel is denser, and denser materials always slow sound
Steel contains more air pockets
Its particles are close together and strongly bonded, so vibrations are passed on quickly
Sound gains energy from the metal
28.
Which part of the ear converts vibrations into electrical nerve signals?
The eardrum
The ossicles
The ear canal
The cochlea
29.
Why is ultrasound, rather than X-rays, used for scanning a developing fetus?
Ultrasound is non-ionising and is partly reflected at tissue boundaries, giving depth from echo times
Ultrasound is louder than X-rays
Ultrasound passes straight through all tissue without reflecting
X-rays cannot travel through water
30.
Which change to a sound makes its pitch higher?
Increasing its amplitude
Increasing its frequency
Moving it into a denser gas
Making it travel further
31.
Frequency, amplitude and waveform shape each affect how a sound seems to a listener. Which pairing is correct?
Amplitude – pitch
Frequency – loudness
Frequency – pitch
Waveform shape – loudness
32.
Sonar, prenatal scans, earthquakes and chatting friends involve sounds of very different frequency. Which pairing is correct?
Earthquake rumble – ultrasound
Prenatal scanning – infrasound
Normal conversation – ultrasound
Sonar depth finding – ultrasound
33.
Sound crosses air, water, steel and empty space at very different rates. Which pairing is correct?
Water – about 1500 m/s
Air – about 1500 m/s
Steel – about 343 m/s
Vacuum – about 343 m/s
34.
Thunder is heard 3.0 s after a lightning flash. With sound travelling at 340 m/s, the storm is about _____ away.
510 m
113 m
2040 m
1020 m
35.
Sound with a frequency below 20 Hz is called _____.
ultrasound
an echo
a rarefaction
infrasound
36.
The loudness of a sound is determined by the _____ of the sound wave.
amplitude
frequency
speed
wavelength
37.
A reflected sound heard a short time after the original is called an _____.
overtone
echo
infrasound
amplitude
38.
In the diagram of a moving sound source, observer Y receives sound of shorter wavelength than the sound emitted by a stationary source. True or false?
Dr Dabour Hub Academy - figure 10
True
True, because the waves travel more slowly behind the source
True only when the source stops moving
False
39.
Repeating the timing several times and taking a mean reduces the effect of random errors from reaction time. True or false?
False
False, because means only remove systematic errors
True
True only when the same person times every trial
40.
In the echo clap method, a student uses v = d/t with d as the distance to the wall. This gives a speed that is too small by a factor of 2. True or false?
False
False, because the echo travels only one way
True only when the wall is very close
True
41.
Sound is a longitudinal wave, so the air particles vibrate back and forth along the direction the sound travels. True or false?
False
False, because sound particles vibrate at right angles to the wave
True
True only when the sound is very loud
42.
A sound of 80 dB is twice as intense as a sound of 40 dB. True or false?
True
True, because the decibel number doubles
True only when both sounds have the same frequency
False
43.
Sound travels faster in warm air than in cold air. True or false?
True
False
False, because cold air is denser so sound goes faster
True only when the sound is ultrasonic
44.
A person can hear an ultrasonic dog whistle if they stand close enough to it. True or false?
True
False
True, because loudness decides whether a sound is audible
True only when the whistle is blown very hard
45.
Soft, porous materials such as curtains absorb sound well, reducing echoes in a room. True or false?
False
False, because soft materials reflect sound best
True
True only when the room is empty
46.
The upper frequency limit of human hearing tends to fall with age. True or false?
False
False, because older people hear higher frequencies
True only when the person is exposed to loud noise
True
47.
In the Doppler effect for a moving source, the source itself changes the frequency at which it vibrates. True or false?
False
True
True, because moving sources vibrate faster
True only when the source moves faster than sound
48.
Prolonged exposure to sound above about 85 dB can damage hearing. True or false?
False
True
False, because only sounds above 130 dB cause damage
True only when the sound is below 20 Hz
49.
If the distance from a point source of sound doubles, the intensity halves. True or false?
True
True, because intensity is inversely proportional to distance
False
True only when the source is in water
50.
A microphone converts the pressure variations of a sound wave into an electrical signal that can be displayed on an oscilloscope. True or false?
False
True
False, because a microphone produces sound from electrical signals
True only when the sound is ultrasonic
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