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HIA International — Grade 8

Unit 1: Photosynthesis and the carbon cycle

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Unit 2: Properties of materials

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Unit 3: Forces and energy

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Unit 4: Maintaining life

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Unit 5: Reactivity

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Unit 6: Sound and space

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Unit 7: Genes and inheritance

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Unit 8: Rates of reaction

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Unit 9: Electricity

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Quiz

Interference Of Sound – Quiz

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Interference Of Sound HIA Science quiz: free practice for HIA International. Work through this Interference Of Sound HIA Science quiz and get instant feedback on every answer. If you get stuck, review the 24.7 Interference Of Sound – Notes lesson. More practice: HIA International — all units. Syllabus: Cambridge Lower Secondary programme.

  • Questions count: 50
  • Passing grade: A-
  • Time limit:
Start Quiz
1.
Two identical sound waves meet exactly out of phase. What happens?
Nothing happens
They add and the sound is louder
The pitch rises
They cancel and the sound is quieter
2.
Why do you hear loud and quiet bands walking between two speakers?
The room absorbs sound
The speakers keep changing volume
Your ears get tired
The waves interfere constructively and destructively at different points
3.
How do noise cancelling headphones work?
They raise the pitch
They produce a wave out of phase with the noise
They amplify the noise
They block the ear completely
4.
What is interference?
The absorption of sound by soft materials
The speed of sound in air
What happens when two waves meet and combine
The reflection of sound from a wall
5.
What is constructive interference?
Sound being absorbed
Waves cancelling to give silence
Sound reflecting from a surface
Waves adding together to give a louder sound
6.
What does in phase mean?
Two waves in a vacuum
Two waves of different loudness
Two waves whose compression meets a rarefaction
Two waves whose compressions arrive together
7.
What does out of phase mean?
The waves have different speeds
A compression of one wave meets a rarefaction of the other
The waves have stopped
The compressions arrive together
8.
What does interference show about sound?
Sound really does travel as a wave
Sound travels in a vacuum
Sound has no energy
Sound is made of tiny balls
9.
What are dead spots in a room?
Places where the speakers are broken
Points where sound is loudest
Points where waves from two speakers cancel
Places with no air
10.
What causes beats when two tuning forks are sounded together?
They have exactly the same frequency
The forks touch each other
One fork is louder
Their frequencies are close, so the waves drift in and out of phase
11.
How can beats help a musician tune an instrument?
Beats cannot help
Play louder until beats stop
Make the beats faster
Adjust until the beats slow down and disappear, showing the frequencies match
12.
The diagram shows two waves meeting. What kind of interference is shown?
Dr Dabour Hub Academy - figure 1
Constructive: the waves are in phase and add
No interference
Reflection
Destructive: the waves cancel
13.
The diagram shows two waves meeting. What will a listener hear?
Dr Dabour Hub Academy - figure 2
A higher pitch
A lower pitch
Near silence
A louder sound
14.
In the diagram, why is the sound loud at point X?
Dr Dabour Hub Academy - figure 3
X is the same distance from both speakers, so the waves arrive in phase
X is behind the speakers
X is closer to one speaker
The waves cancel at X
15.
Using the graph, how far apart are neighbouring loud spots?
Dr Dabour Hub Academy - figure 4
About 1.25 m
About 0.5 m
About 5 m
About 2.5 m
16.
Using the graph, what is the difference between the loudest and quietest levels?
Dr Dabour Hub Academy - figure 5
50 dB
90 dB
10 dB
40 dB
17.
The quiet spots in the graph are 50 dB, not silent. What is the most likely reason?
Dr Dabour Hub Academy - figure 6
The speakers are in phase
Reflections from the walls add extra sound
Sound cannot cancel at all
The microphone is broken
18.
The diagram shows the combined wave from two tuning forks. How many beats are heard each second?
Dr Dabour Hub Academy - figure 7
100
104
204
4
19.
In the noise cancelling diagram, how does the headphone wave compare with the engine noise?
Dr Dabour Hub Academy - figure 8
It has a much higher frequency
It is out of phase with it
It is in phase with it
It is a random wave
20.
The result in the noise cancelling diagram is not completely flat. Why?
Dr Dabour Hub Academy - figure 9
The waves are in phase
The engine stopped
The headphone wave is slightly smaller than the noise wave
Sound travels in a vacuum
21.
Using the bar chart, which sound is reduced most by noise cancelling?
Dr Dabour Hub Academy - figure 10
High clicks
All reduced equally
Low engine hum
Middle voices
22.
Using the bar chart, why can passengers still hear voices with noise cancelling on?
Dr Dabour Hub Academy - figure 11
The headphones amplify voices only
Voices are ultrasound
The system mostly cancels steady low sounds, not changing voices
Voices travel faster
23.
What is the fourth step in the flow chart?
Dr Dabour Hub Academy - figure 12
Waves overlap
Two sources produce sound
A pattern forms
At other points a compression meets a rarefaction
24.
Use the table. Which situation produces a louder sound?
Noise cancelling headphones
Two speakers in step
Dead spots
Two speakers out of step
25.
Use the table. What is the use of two tuning forks close in frequency?
Comfort on a plane
Concert sound
Tuning an instrument
Dead spots
26.
Use the table. At which position is destructive interference strongest?
Position 1
Position 2
Position 3
Position 4
27.
Use the table. How many beats per second are heard from forks of 256 Hz and 260 Hz?
256
260
4
516
28.
Use the table. A musician's string gives 3 beats per second with a 440 Hz fork. After tightening, it gives 5 beats per second. What should she do?
Change the fork
Leave it as it is
Tighten it more
Loosen the string, because it is now further above 440 Hz
29.
A student's notes contain one mistake. Which row?
Noise cancelling - out of phase wave
In phase - louder sound
Out of phase - waves cancel
In phase - waves cancel
30.
Use the table. What is the mean distance between loud spots?
3.6 m
1.2 m
1.1 m
1.3 m
31.
Use the table. Which change would make the loud spots further apart?
Turning the speakers up
Using a higher frequency note
Using a lower frequency note
Moving the listener closer
32.
Why should both speakers be connected to the same signal generator in an interference experiment?
To change the pitch randomly
To make them louder
To stop interference
So the waves have the same frequency and a steady phase relationship
33.
Why is a sound level meter better than the ear for finding the quiet spots?
It makes the sound louder
It changes the frequency
It gives measured values, so positions can be compared precisely
Ears cannot hear sound
34.
A student wants to show that interference depends on frequency. Which plan is best?
Use one speaker only
Change the speaker positions and frequency together
Keep the speakers fixed, play different frequencies, and measure the distance between loud spots each time
Change the room each time
35.
Which pairing of situation and result is correct?
Two speakers out of step - waves cancel
Echo - clearer sound
Noise cancelling - louder sound
Two speakers in step - waves cancel
36.
Which pairing of observation and explanation is correct?
Silence - waves in phase
Loud spot - waves arrive out of phase
Dead spot - waves arrive out of phase
Beats - identical frequencies
37.
Use the table. At which microphone position are the two waves most nearly in phase?
Position D
Position A
Position C
Position B
38.
Why does a sound engineer place concert speakers so that their sound arrives in step at the audience?
To avoid dead spots caused by destructive interference
To make the pitch higher
To stop echoes completely
To use less electricity
39.
Match the term to its description: Noise cancelling
Using a deliberately out of phase wave to reduce unwanted sound
Waves adding to give a louder sound
Waves meeting and combining
Two waves in phase
40.
Waves cancelling to give a quieter sound is _____ interference.
absorbed
destructive
reflected
constructive
41.
Two waves whose compressions arrive together are in _____.
phase
step size
range
tune
42.
Forks of 440 Hz and 443 Hz give _____ beats per second.
883
443
440
3
43.
Two waves in phase add to give a louder sound. True or false?
False
True
True, but only for light
False, they cancel
44.
Noise cancelling headphones make a wave in phase with the noise. True or false?
True, to double it
False, they make no wave
True
False
45.
Walking between two speakers you pass through loud and quiet bands. True or false?
True
True, but only outdoors
False, the sound is the same everywhere
False
46.
Interference can only happen if the two sounds have similar frequencies. True or false?
False, any two sounds give a steady pattern
False, only very different frequencies interfere
True
False
47.
Destructive interference can give near silence. True or false?
True, but only underwater
False, it always makes sound louder
True
False
48.
Two forks of 300 Hz and 302 Hz produce 2 beats per second. True or false?
False, they produce no beats
False
True
False, they produce 602 beats
49.
Echoes in a large empty hall can blur sound because a delayed wave adds later. True or false?
False, echoes make sound clearer
False
True, but only with one speaker
True
50.
In the in-phase diagram, the result wave has about twice the amplitude of each separate wave. True or false?
Dr Dabour Hub Academy - figure 13
False, it has half the amplitude
True
False, it is flat
False
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Part of Unit 6: Sound and space — see every lesson and quiz in this unit.
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