Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Units (Waves)
82 practice questions
Topics covered
Practice questions
71–80 of 82
Question 71
2 marks · Easy
Answer and see the solution →A stationary ambulance travels past a person. While the ambulance moves away, the person notices a change in the siren’s pitch.
(a)[1 mark]Describe what happens to the pitch of the siren as the ambulance moves away.
(b)[1 mark]Explain why this change happens, using wavefronts in your explanation.
Question 72
2 marks · Easy
Answer and see the solution →Why does the Doppler effect happen for both sound and light waves? Give a reason in terms of wave properties.
Question 73
3 marks · Easy
Answer and see the solution →A van is moving while playing music from a speaker attached to its roof.
(a)[2 marks]Describe what would happen to the frequency of the music heard by someone standing in front of the moving van, compared to someone standing behind it.
(b)[1 mark]Explain why this happens.
Question 74
2 marks · Normal
Answer and see the solution →State what happens to the frequency of sound waves from a moving source as it moves towards a stationary observer. Explain your answer.
Question 75
3 marks · Normal
Answer and see the solution →The speed of sound in a material is 1500 m/s. Calculate the frequency of a sound wave in this material if its wavelength is 2.0 m. Give your answer to 2 significant figures.
Question 76
3 marks · Normal
Answer and see the solution →A stationary ambulance is sounding its siren at a constant frequency. Describe and explain what happens to the pitch of the siren for an observer as the ambulance starts to move away from them.
Question 77
1 mark · Normal
Answer and see the solution →Which one of the following statements best describes the Doppler effect?
- A.The change in frequency of a wave observed when the source is moving relative to the observer.
- B.The reflection of waves from a hard surface.
- C.The bending of waves when they pass through a gap.
- D.The decrease in energy of a wave as it moves further from the source.
Question 78
3 marks · Normal
Answer and see the solution →Explain why the frequency of a siren heard by a person changes when a fire engine moves past them at a constant speed.
Question 79
4 marks · Normal
Answer and see the solution →A student observes a train moving towards a platform while sounding its horn.
(a)[1 mark]Describe what happens to the frequency of the sound heard by a person standing on the platform as the train approaches.
(b)[2 marks]Explain your answer to part (a).
(c)[1 mark]What will happen to the frequency of the sound as the train passes and moves away from the platform?
Question 80
3 marks · Normal
Answer and see the solution →Describe a simple experiment you could carry out to demonstrate the Doppler effect for sound. Explain what you would expect to observe.