Student Login

Home›Chapters›Wave Motion PYQs›Doppler Effect›Question 60

JEE Main 2017 · Doppler Effect

Doppler Effect question from JEE Main 2017

Q60JEE Main 2017Medium

Doppler Effect

An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer? (speed of light = 3 ×108 ms–1)

Show answer and solution

Answer: (d)

For light use the relativistic Doppler formula: $f' = f\sqrt{\dfrac{1 + \beta}{1 - \beta}}$ with $\beta = 0.5$ .
$f' = 10\sqrt{\dfrac{1.5}{0.5}} = 10\sqrt{3} \approx 17.3\text{ GHz}$
So the answer is (d) 17.3 GHz.

Report a mistake

More questions on Doppler Effect

Two engines pass each other moving in opposite directions with uniform speed of 30 m/s…JEE Main 2016 (9 Apr, Shift 1)
A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff…NEET 2016 (Phase 1)
A toy-car, blowing its horn, is moving with a steady speed of 5 m/s, away from a wall. An…JEE Main 2016 (10 Apr, Shift 1)
A source of sound S emitting waves of frequency 100 Hz and an observer O are located at…NEET 2015 (AIPMT)
A bat moving at 10 ms ⁻¹ towards a wall sends a sound signal of 8000 Hz towards it. On…JEE Main 2015 (10 Apr, Shift 1)
A source of sound emits sound waves at frequency f0. It is moving towards an observer…JEE Main 2015 (11 Apr, Shift 1)
A train is moving on a straight track with speed 20 ms⁻¹. It is blowing its whistle at…JEE Main 2015
Two factories are sounding their sirens at 800 Hz. A man goes from one factory to other…JEE Main 2014 (11 Apr, Shift 1)