Question

police use doppler radar to detect speeding cars. explain how the doppler effect is used in this application.

Answer 1

Doppler effect, the term given as a regard to Austrian mathematician Christian Doppler.

doppler effect is an apparent change in frequency or wavelength of a wave caused by relative motion between the source and the observer.

short waves emitted from the doppler radar are directed towards the moving vehicle, these directed waves are reflected back towards the instrument( doppler radar) , after the waves strikes the vehicle body, by calculating the shift in the wavelength ( when car approaches wavelength decreases and when it leaves behind the radar the wavelength increases) the velocity of the speeding car be determined.

but the problem arises when the car and the doppler radar both are in motion.