THE DOPPLER SHIFT EFFECT
The Doppler shift effect
consists in the change of wave frequency registered by the
receiver. The change is the difference between the wavelength in
the situation when the relative motion of the source proceeds from
or to the waves receiver and the situation when the source doesn't
move. For light, as the source moves closer to the observer, the
spectrum is shifted toward violet; as the source distances from the
observer; the spectrum is shifted toward red. The shift of the
spectral lines makes it possible to determine the velocity of the
waves' source movement with the respect to the receiver
(observer).
