Activity 10.4 – Science Form 2 Chapter 10


Question:
Aim: To study the Doppler effect of sound using an air horn.

Apparatus: Air horn

Instruction
1. You are required to stand in the middle of the assembly area.

2. Ask your friend to sound an air horn while running past you.

3. Record the pitch of the sound of the air horn during and after your friend has run past you.

Questions
1. What happens to the pitch of the sound when the air horn is sounded while passing by the observer?

2. State the relationship between the frequency of sound and the distance of the sound source from the observer.

3. Does the person who carries the sound source also feel the change in the pitch of the sound? Give a reason.

Answer:
1. Pitch of sound increases.

2. The nearer the distance between sound source and observer, the higher the frequency of sound.

3. No, because there is no relative movement from the person who carries the sound source and the sound source.

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