The Doppler Effect

What is the Doppler Effect?

The Doppler effect is a quantitative analysis that shows how the frequency heard by a stationary observer depends on whether the observer sees the source approaching or receding

This means that waves have different observed frequencies when the wave source is in motion

A Diagram

Direction of motion

Sound waves

Equations for a moving source

The equation for a receding object is

The equation for an approaching object isvvf

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0

1

vvf

f0

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at travelingis wave thespeed The

at moving is source thespeed The

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Equations for a moving observer

For an observer moving towards the source

For an observer moving away from the source

00 )1( fv

vf

00 )1( fv

vf

at travelingis wave thespeed The

at moving isobserver thespeed The

wave theoffrequecy actual the

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For light waves

When light waves are emitted from a source moving away from you the light appears to be redshifted, as it is distorted back in the color spectrum towards red

Also, when light is emitted for a source moving towards you it appears to be blueshifted, or moved up in the color spectrum towards blue

Diagram of light shifting

Direction of motion

Light waves

The Doppler double shift

This occurs when a wave is reflected off of a moving object and it indicates the frequency shift and it has application in detecting blood flow rates and radar

v

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