Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Light and Sound
70 practice questions
Topics covered
Practice questions
21–30 of 36 · Normal
Question 21
4 marks · Normal
Answer and see the solution →Read the passage: 'A bundle of optical fibres is used in a medical endoscope to allow a doctor to see inside a patient’s stomach.'
(a)[2 marks]Describe how the endoscope uses optical fibres to allow the doctor to see inside the body.
(b)[2 marks]State two reasons why using an endoscope made with optical fibres is an advantage for the patient, compared to traditional open surgery.
Question 22
2 marks · Normal
Answer and see the solution →State two different applications of optical fibres, other than medical endoscopes, and briefly describe how they work.
Question 23
4 marks · Normal
Answer and see the solution →A laser sends light into an optical fibre at an angle of incidence of 72° to the normal. The critical angle for the core–cladding boundary is 60°.
(a)[2 marks]Explain whether the light will be totally internally reflected at the core–cladding boundary.
(b)[2 marks]If the refractive index of the core is 1.50, calculate the maximum refractive index of the cladding for total internal reflection to occur at this boundary. (Give your answer to 2 decimal places.)
Question 24
4 marks · Normal
Answer and see the solution →A drum is struck once to produce a sound in air. The drum's skin vibrates rapidly after being hit.
(a)[1 mark]State whether the sound wave produced by the drum is longitudinal or transverse.
(b)[2 marks]Explain how the sound travels from the drum to a listener's ear.
(c)[1 mark]Describe what would happen to the sound if the drum was played inside a vacuum.
Question 25
4 marks · Normal
Answer and see the solution →A student investigates the speed of sound in air using the echo method. She stands 120 m from a large wall. She claps her hands and starts a stopwatch when she sees the clap, stopping the watch when she hears the first echo. The time recorded is 0.7 seconds.
(a)[1 mark]Calculate the distance travelled by the sound wave from the student to the wall and back.
(b)[3 marks]Calculate the speed of sound in air in this experiment. Give your answer to 2 significant figures. Use the equation:
Question 26
3 marks · Normal
Answer and see the solution →You have a signal generator, a loudspeaker, a microphone and an oscilloscope. You want to find the frequency of a sound wave produced by the loudspeaker.
(a)[2 marks]Describe how you would use the oscilloscope to find the frequency of the sound.
(b)[1 mark]You observe that one complete wave on the oscilloscope trace takes 0.004 s. Calculate the frequency of the sound wave.
Question 27
3 marks · Normal
Answer and see the solution →Sound waves can be reflected and refracted much like light.
(a)[1 mark]Describe what happens when a sound wave meets a flat, hard surface such as a wall.
(b)[2 marks]Explain how ships use echoes to measure the depth of the sea below them.
Question 28
4 marks · Normal
Answer and see the solution →A table shows the results from five measurements of the speed of sound using the echo method.
Echo timing results Attempt Distance to wall (m) Time for echo (s) 1 100 0.60 2 100 0.59 3 100 0.62 4 100 0.61 5 100 0.58 (a)[1 mark]Explain why the experiment was repeated several times and an average taken.
(b)[1 mark]Calculate the average time for the echo.
(c)[2 marks]Calculate the average speed of sound from the average time, using:
where the sound travels from the student to the wall and back.
Question 29
1 mark · Normal
Answer and check →Which statement about sound waves is correct?
- A.Sound waves in air are transverse waves.
- B.Sound waves cannot be reflected.
- C.Sound waves travel faster in solids than in air.
- D.Sound waves can travel through vacuum.
Question 30
4 marks · Normal
Answer and see the solution →Two musical instruments, a violin and a cello, each produce a note and their sounds are shown as oscilloscope traces.
(a)[2 marks]Describe how you can tell from the trace which instrument produces the higher-pitched note.
(b)[2 marks]Explain what happens to the loudness of the sound if the amplitude of the wave on the oscilloscope is increased.