A police radar unit transmits microwaves of frequency 2.00 × 1010 Hz, and their

Question

A police radar unit transmits microwaves of frequency 2.00 × 1010 Hz, and their speed in air is 3.00 108 m/s. Suppose a car is receding from the stationary police car at a speed of 146 km/h. (a) What is the frequency difference between the transmitted signal and the signal received from the receding car? kHz (b) Suppose the police car is, instead, moving at a speed of 70 km/h in the same direction as the other vehicle. What is the difference in frequency between the emitted and the reflected signals? kHz

Please show all the steps

Explanation / Answer

By doppler effect

New frequency=f*((c+vr)/(c+vs))

Given vr=-146km/hr=-40.56 m/s

We got new frequency=1.99 *10(10) hz

Difference=3 khz

If vs=70km/hr=19.44 m/s

Putting the value we got

Difference=2 khz

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