The radar used by police to check over-speeding vehicles works on the

The radar used by police to check over-speeding vehicles works on the principle of

Raman effect

Induction effect

Doppler effect

Coulomb effect

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Answer is Wrong!

This question was previously asked in

UPSC CAPF – 2020

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The radar used by police to check over-speeding vehicles works on the principle of the Doppler effect.

The Doppler effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. Police radar guns emit radio waves towards a moving vehicle. When these waves reflect off the vehicle, their frequency is shifted. If the vehicle is moving towards the radar, the reflected waves have a higher frequency; if moving away, they have a lower frequency. The radar unit measures this frequency shift and calculates the vehicle’s speed based on the magnitude of the shift.

The Raman effect involves inelastic scattering of photons. The Induction effect relates to the production of an electromotive force across an electrical conductor in a changing magnetic field. The Coulomb effect describes the electrostatic interaction between charged particles. None of these principles are the basis for how police speed radar operates.

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