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### Question

#### A radar operates at wavelength 50.0 cm. If the beat freqency between the transmitted singal and the singal reflected from aircraft ( ) is 1 kHz, then velocity of the aircraft will be

- 800 km/hr
- 900 km/hr
- 1000 km/hr
- 1032 km/hr

#### The correct answer is: 900 km/hr

#### when source is fixed and observer is moving towards it

when source is moving towards observer at rest

= 900 km/hr

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