Question

A rocket is going away from the earth at a speed 0.2c, where c = speed of light. It emits a signal of frequency 4 x 10⁷ Hz. What will be the frequency as observed by an observer on the earth?

(A) 4 x 10⁶ Hz

(B) 3.2 x 10⁷ Hz

(C) 3 x 10⁶ Hz

(D) 5 x 10⁷ Hz

Answer 1

Correct option is (B) 3.2 x 10⁷ Hz

\(\therefore\)  Frequency of the signal as observed by the observer on earth