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GCSE Questions - Waves

Q11. A radar gun is used to determine the speed of a cricket ball during a cricket match. The radar gun emits a beam of microwaves. The microwaves are reflected from the moving ball, as shown in the diagram.

Comparing the microwaves emitted by the radar gun with the microwaves reflected from the cricket ball enables the speed of the ball to be determined.

(a) What is the name given to the effect used to determine the speed of the cricket ball?

The doppler effect For notes - See here

[1 mark]

(b) Compare the wavelength, frequency and speed of the reflected microwaves with the wavelength, frequency and speed of the microwaves emitted by the radar gun.

The ball is moving towards the gun - therefore:

the wavelength of the microwaves will be shorter - will decrease.

The frequency of the wavelengths will increase - be higher.

The speed of the microwaves will be the same - the speed of light.

[3 marks]

(Total 4 marks)