Class 12 Physics Sound Test
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Test on Sound
Name: ________________
Circle the one best alternative unless the question specifically states that there may be one or more correct
answers.
Q.1
Sound is
A a wave which travels through any material or a vacuum.
B a wave which travels only through air.
C a wave which travels through many materials but not a vacuum
D particles which travel through most things.
Q.2
Sound in air can best be described as a
A transverse pressure wave of compressions and rarefactions in air.
B transverse displacement wave which travels through air.
C transverse polarised pressure wave in air.
D longitudinal wave of air compressions and rarefactions.
Q.3
The speed of sound in air is about
A 100 m/s
B 300 m/s
C 1000 m/s
D 3 x 108 m/s
Q.4
We set up a loud speaker at the front of the room at ear level. the sound waves that pass thru' the room
towards you will cause the air molecules in their path to
A vibrate vertically up and down.
B vibrate horizontally back and forward.
C vibrate both vertically and horizontally.
D move toward you in waves.
Q.5
The ‘pitch’ of a musical note is normally given in terms of its
A amplitude.
B frequency.
C wavelength.
D speed.
Q.6
Which of the alternatives (A to D) in the previous question
indicates the loudness of the note?
Ans: ______
Q.7
The speed of any periodic wave is given by
Note: one or more of these may be correct.
A the wavelength times the frequency.
B the wavelength times the period.
C the wavelength divided by the frequency.
D the wavelength divided by the period.
Q.8
The first diagram below shows part of a sound wave of high (H) and low (L) pressure areas travelling to
the right. The points A to D represent various positions along the wave at time zero. Point A, for example
is in the centre of a high pressure area at the time T = 0 shown. The sound wave may be represented by a
graph of pressure variation with time (P-T), shown in the first graph, or by a graph of pressure variation
with position (P-X), the second graph.
a) At which point, A to D, would the P-T graph shown represent the
pressure variation over the next few milliseconds?
b) At which point, A to D, would the P-X graph shown represents the pressure variation to the right of the
point at that time, T = 0.
c) What is the speed of sound on this occasion? (Show working.)
Q.9
The normal frequency range of hearing in a young person (who hasn't been to too many pop concerts) is
about
Class 12 Physics Sound Test
A 10 Hz to 10 kHz
C 30 Hz to 30 kHz
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B 20 Hz to 20 kHz
D 100 Hz to 10,000 Hz
In the following questions assume that the threshold of hearing occurs at a sound power intensity of
I = 1.0 x 10-12 W/m5
Q.10 If the level of sound in the room is said to be 70 dB this means that the sound power intensity is
A 7.0 x 10-12 W/m5
B 1.0 x 10-7 W/m5
-5
C 1.0 x 10 W/m5
D 70 x 10-12 W/m5
Q.11 If the level of sound in the room increases to 76 dB (from 70 dB) the sound power intensity has gone up
A only a fraction.
B double
C quadruple
D six times
Q.12 If the sound power intensity in the room doubles we will
A hear a big difference in the loudness.
B notice only a small difference.
C not hear any difference at all.
D be deafened.
Q.13 The sound level at a rather noisy party (with disco) could be
A 40 dB
B 60 dB
C 80 dB
D 100 dB
Q.14 A trumpet is playing at a level of 90 dB when the french horn joins in at 85 dB. Together they will
generate a level of about
A 90 dB
B 91 dB
C 93 dB
D 175 dB
Q.15 If a single violin produces 65 dB of sound how much will 20 violins produce?
_________dB
Q.16 I am 10 m from a band in the open air and the sound level is 95 dB.
a) If I move back another 10 m (to 20 m) what will the level be?
_______dB
b) How far away do I have to be to reduce the level to 92 dB?
_______m
Q.17 I am listening to some music through an open door at the concert hall but I can't see any of the orchestra. I
will hear
A the violins better than the cellos.
B the cellos better than the violins.
C there will be no difference in the two.
D we would have to go to a concert to find out.
Q.18 If we listen to sound of a single frequency from a loudspeaker which is reflecting back from a solid brick
wall we hear minimums and maximums at certain distances from the wall. The spacing between the nodes
will be
A 3λ
B 2λ
C 1λ
D 2λ
Q.19 The sound of a flute is different to, say, a clarinet playing the same note because
A they produce different fundamental frequencies.
B they produce sound of different amplitudes.
C one produces transverse waves and the other longitudinal waves.
D they produce a different range of overtones.
Class 12 Physics Sound Test
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For the following questions, where necessary: Take the speed of sound in air as 340 m/s
Q.20 Virtually all musical instruments depend on >resonance=. Which of these best describes what is meant by
resonance?
A The superposition principle which says that the overall displacement of a wave is the vector
addition of the individual displacements of separate waves.
B When waves coming from two or more sources reach the same region they will combine in such a
way as to cause constructive or destructive interference.
C Waves trapped in a confined space will always interfere with each other to produce a bigger wave.
D Waves trapped in a confined space will sometimes interfere with each other to produce standing
waves.
Q.21 When resonance occurs in a flute it will only occur
Note: one or more of these may be correct.
A at certain frequencies.
B at certain wavelengths.
C at certain amplitudes.
D if the player blows at the right frequency.
Q.22 A flute can be regarded as an air tube open at both ends. This means that when it is played, the pressure
variation standing waves will be such that at the ends there will be
A nodes at both ends.
B antinodes at both ends.
C a node at one end and an antinode at the other end.
D a node or an antinode depending on the note being played.
Q.23 If a flute is 65 cm long (including end corrections) what is the frequency of the lowest note it will be able
to play?
Show your working:
Ans: ________Hz
Q.24 Given your answer to the previous question, what will be the frequency of the first overtone that the flute
will produce?
Ans: ________Hz
Q.25 A clarinet is effectively an air tube closed at one end and open at the other. This means that the
wavelength of the fundamental note produced will be
A equal to the length of the clarinet.
B half the length of the clarinet.
C twice the length of the clarinet.
D four times the length of the clarinet.
Q.26 The overtones produced in the clarinet will be
A all multiples of the fundamental.
B odd multiples of the fundamental.
C even multiples of the fundamental.
D it depends on the note being played.
Q.27 If the fundamental frequency of the clarinet is 200 Hz, what is the effective length of the clarinet?
Show working:
Ans: _______m
Two loudspeakers (which we can assume radiate sound in all directions) are set up in a space where there are few
echos. They are both fed with the same 85 Hz signal and are in phase. Initially they are placed 6 metres apart.
Q.28 What is the wavelength of the sound produced?
Show working:
Ans: _______m
Class 12 Physics Sound Test
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The wavelength is now changed to 2 metres. I walk from one speaker to the other noting the minimums in the
sound I hear.
Q.29 How many minimums do I hear? Show your working and explain the answer:
Ans: _______
Q.30 I now walk away from the speakers until I find myself 10 m from one and 11 m from the other. At this
spot the sound I hear is
A slowly rising and falling in volume.
B slowly rising and falling in pitch.
C steady and loud.
D steady and quiet.
Q.31 I now walk in a quarter circle from the position directly in front and midway between the two speakers to a
position which is in a line with them. How many minimums in the sound level would I notice?
Ans: _______
Why?
Q.32 When I am directly in line with the two speakers (to the side) do I notice a minimum or a maximum in the
sound level?
Ans: _____________
Q.33 An organ pipe closed at one end and open at the other produces a fundamental frequency of 100 Hz. What
are the frequencies of each of the following:
a) The 1st harmonic
_______ Hz
b) The 1st overtone
_______ Hz
c) The 3rd harmonic
_______ Hz
d) The 3rd overtone
_______ Hz
Q.34 A flute is tuned to the rest of the orchestra by adjusting its length slightly. Compared to the length on a
cool day, on a hot day (when the speed of sound is higher) to tune the flute to the correct frequency the
length will need to be
A slightly greater
B slightly less
C a lot less
D unchanged
Class 12 Physics Sound Test
ANSWERS
Q.1
Q.2
Q.3
Q.4
Q.5
Q.6
Q.7
Q.8
Q.9
Q.10
Q.11
Q.12
Q.13
Q.14
Q.15
Q.16
Q.17
Q.18
Q.19
Q.20
Q.21
Q.22
Q.23
Q.24
Q.25
Q.26
Q.27
Q.28
Q.29
Q.30
Q.31
Q.32
Q.33
Q.34
C
D
B
B
B
A
A,D
a) D b) A c) 4m/12ms = 333 m/s
B
C
C
B
D
B
78 dB
a) 89 dB b) 14 m
B
B
D
D
A,B
A
340/1.3 = 262 Hz
523 Hz
D
B
3 x 340/200 = 0.425 m
340/85 = 4 m
6 nodes
D
3
Max
100 Hz, 300 Hz, 300 Hz, 700 Hz
A
Test from Keith Burrows. Originally in Word Perfect 8. If you would prefer it in WP8 format email me at:
keithb@a1.com.au
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