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Waves

The Doppler Effect (continued)

Both the effects illustrated in the diagrams above result in a change in the apparent frequency of the sound (as measured by the observer).

The Doppler Effect is the apparent change in the frequency of a sound wave due to the relative motion of source and observer.

If the frequency of the emitted sound is f and the frequency measured by the observer is f’ then the Doppler shift, Df, is defined as

Df = f’ – f

The magnitude of the Doppler shift depends on

a) the frequency of the emitted sound, f

b) the relative velocity of source and observer.

The relative Doppler shift (defined as Df/f) depends only on the relative velocity of source and observer.

 

 

© David Hoult 2008