WavesEdexcel GCSE Physics: Topic test

20 questions, 54 marks

Edexcel GCSE Physics

Waves topic test

Total 54 marks

Name

Class

Date

1
A harbourmaster watches waves entering a harbour from the open sea. Using a stopwatch and a marker post, she counts 8 complete waves passing the post in 20 seconds, and measures the distance between two adjacent wave crests as 3.5 m.
(a)
What is the frequency of the waves entering the harbour?
[1 mark]
A0.4 Hz
B2.5 Hz
C160 Hz
D0.04 Hz
(b)
What is the speed of the waves entering the harbour?
[1 mark]
A8.75 m/s
B1.4 m/s
C0.114 m/s
D14 m/s
(c)
State whether these harbour waves are transverse or longitudinal, and explain how the direction a floating buoy moves compares with the direction the wave travels, as the wave passes it.
[2 marks]
Total for question 1: 4 marks
2
An engineer at a chemical plant uses an ultrasonic thickness gauge to check the wall thickness of a steel pipe without cutting into it. The gauge sends a short pulse of ultrasound into the pipe wall, and a sensor detects the pulse after it reflects off the far (outer) surface of the pipe wall and returns.
(a)
Which frequency range is classified as ultrasound?
[1 mark]
ABelow 20 Hz
BBetween 20 Hz and 20 000 Hz
CAbove 20 000 Hz
DExactly 20 000 Hz
(b)
Why is ultrasound, rather than audible sound, used for this kind of thickness gauge?
[1 mark]
AUltrasound travels faster than audible sound through steel
BUltrasound cannot be reflected by metal surfaces, so it passes straight through until it reaches an edge
CUltrasound has a lower frequency than audible sound, so it penetrates metal more easily
DUltrasound has a short wavelength, allowing it to be focused into a narrow, precise beam, and it is inaudible so does not disturb nearby workers
(c)
The gauge measures a time of 4.0 microseconds between sending the pulse and detecting its reflection, and the speed of ultrasound in steel is 5900 m/s. Calculate the thickness of the pipe wall, explaining why you must account for the pulse travelling to the outer surface and back.
[2 marks]
Total for question 2: 4 marks
3
An acoustic engineer is testing the soundproofing of a wall panel between two recording studios. A loudspeaker in Studio A produces sound waves that strike the panel. Of the sound energy reaching the panel, some is reflected back into Studio A, some is absorbed by the panel's foam lining and converted to heat, and the rest is transmitted through the panel into Studio B.
(a)
Describe, in words, what is meant by each of the terms 'reflected', 'absorbed' and 'transmitted' as used to describe what happens to the sound wave's energy at the panel.
[3 marks]
(b)
The engineer wants to reduce the amount of sound transmitted into Studio B without changing the panel's absorption. Explain, in terms of the wave's energy, why increasing the fraction of sound energy reflected would achieve this, and suggest one property of the panel's outer surface the engineer could change to increase reflection.
[4 marks]
Total for question 3: 7 marks
4
A submarine's sonar system sends a pulse of sound with a frequency of 25 000 Hz through seawater to detect a rock formation on the seabed. The speed of sound in seawater is 1500 m/s. The sonar operator measures a time of 0.80 s between sending the pulse and detecting its echo from the rock formation.
(a)
State whether the 25 000 Hz sonar pulse is ultrasound, infrasound, or within the normal range of human hearing, with a reason. Then calculate the wavelength of this sound wave in seawater, showing your working.
[6 marks]
(b)
Using the sonar operator's measured time of 0.80 s between sending the pulse and detecting the echo, calculate the distance from the submarine to the rock formation, explaining why the total distance travelled by the pulse must be halved to find this distance.
[6 marks]
Total for question 4: 12 marks
5
A geophysical monitoring station uses sensitive microphones to detect infrasound produced by distant volcanic activity, travelling through the atmosphere from a volcano 200 km away. The station also studies elephants, which are known to communicate over long distances using infrasound calls that other elephants can detect even when out of sight of each other.
(a)
Which frequency range is classified as infrasound?
[1 mark]
ABelow 20 Hz
BAbove 20 000 Hz
CBetween 20 Hz and 20 000 Hz
DExactly 20 Hz
(b)
Why can infrasound travel such long distances (such as 200 km) through the atmosphere with relatively little loss of energy, compared with higher-frequency sound?
[1 mark]
AInfrasound travels faster than higher-frequency sound through air
BInfrasound is absorbed less strongly by the atmosphere than higher-frequency sound, so more of its energy remains after travelling long distances
CInfrasound always has a larger amplitude than higher-frequency sound, making it inherently more powerful
DInfrasound is reflected more strongly by air molecules than higher-frequency sound, bouncing it further
(c)
Suggest one advantage to elephants of communicating using infrasound rather than higher-frequency sound, given what you know about how far infrasound can travel.
[2 marks]
Total for question 5: 4 marks
6
An engineer observes an overhead power line cable swaying after being struck by a falling branch. The cable oscillates up and down, completing 15 full oscillations in 6.0 s, and the distance measured between two adjacent points on the cable that are at the top of their swing at the same instant is 8.0 m.
(a)
What is the frequency of the cable's oscillation?
[1 mark]
A0.4 Hz
B90 Hz
C2.5 Hz
D6.0 Hz
(b)
What is the speed of the wave travelling along the cable?
[1 mark]
A3.2 m/s
B10 m/s
C0.31 m/s
D20 m/s
(c)
State whether this wave on the power line is transverse or longitudinal, and explain how the direction of the cable's oscillation compares with the direction the wave travels along the cable.
[2 marks]
Total for question 6: 4 marks
7
A team of technicians wants to measure the speed of sound in air using a large, empty aircraft hangar. One technician claps a wooden block sharply 170 m from a flat end wall of the hangar, while a second technician, standing beside the first, uses a stopwatch to time how long it takes to hear the echo of the clap reflecting back off the wall.
(a)
The stopwatch records a time of 1.0 s between the clap and hearing its echo. Calculate the speed of sound in air used in this experiment, explaining why the total distance travelled by the sound must be twice the 170 m distance to the wall.
[3 marks]
(b)
Suggest two ways the technicians could improve the accuracy of their measured speed of sound using this method.
[4 marks]
Total for question 7: 7 marks
8
A marine biologist studies how dolphins use echolocation to find prey. A dolphin emits a click of ultrasound with a frequency of 110 000 Hz, which travels through seawater (speed 1500 m/s) and reflects off a fish, returning to the dolphin after 0.024 s. Separately, the biologist notes that dolphins can also produce and hear frequencies as low as 75 Hz, within the normal range of human hearing.
(a)
Calculate the wavelength of the dolphin's 110 000 Hz echolocation click in seawater, and calculate the distance between the dolphin and the fish, showing your working for both. Classify the 110 000 Hz click as ultrasound, infrasound, or within the normal human hearing range, with a reason.
[6 marks]
(b)
The biologist notes that dolphins can also produce and hear sounds as low as 75 Hz. Calculate the wavelength of a 75 Hz sound in seawater. Explain why using a high-frequency click (like the 110 000 Hz example above) rather than a low-frequency sound (like 75 Hz) is more useful for a dolphin trying to locate a small fish precisely, linking your answer to wavelength.
[6 marks]
Total for question 8: 12 marks

End of questions