Light is a wave, and as a wave, it experiences the Doppler Effect. Sound is also a wave. We have all experienced the sound of a whistle on a train or siren on a vehicle, and the change in pitch it undergoes at it passes by us.
When we approach a wave, we INCREASE the speed with which the crests pass us, there by increasing the frequency, or shortening the wavelength:
When we move away from a wave (or the source emitting the wave moves away from us), we DECREASE the speed with which the crests pass. This decreases the frequency (increases the wavelength):
Mathematically, the Doppler Effect is described in this way:
Lambda is the wavelength of the light, delta-lambda represents how much the wavelength has shifted, and c is the velocity of the wave. |
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