The Doppler Effect
2 marks · EasyA cyclist rings their bell while moving past a group of people standing on the pavement.
Describe how the sound of the bell changes as the cyclist moves towards, and then away from, the group.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
As the cyclist approaches, the people hear a sound with higher pitch. As the cyclist moves away, the sound is lower in pitch.
Also accept: The frequency increases as the cyclist moves towards, and decreases as the cyclist moves away.
Common mistakes: Describes only getting louder, not pitch/frequency.
Show mark scheme and worked solution
Marking points
B1 · 1 mark · States that the approaching sound is higher in pitch or frequency.
B2 · 1 mark · States that the receding sound is lower in pitch or frequency.
Worked solution
As the cyclist moves towards the people, the sound is higher in pitch (frequency increases). As the cyclist moves away, the pitch drops (frequency decreases).