"Light is always propagated in empty space with a definite velocity cSee my paper on Radar Guns and Einstein's Theories for further details.
which is independent of the state of motion of the emitting body."
How Do Police Radars Really Work?
Since the photon energy, E, is equal to hn, where h = Planck's constant = 6.63 X 10-34 j sec, then
Also, since photon momentum equals h/c, where c is the speed of light, then
where the first term on the RHS represents p for an elastic reflection (i.e., one for which E = 0), and the second term takes into account the change in frequency due to the change in energy.
This equation may be simplified to read
where the final step results from V << c. Now, let V = 60 mph = 27 m/sec, and let = 5 X 108 Hz. Then,
The police radar detector easily detects this frequency shift.