Optics Question 260
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\times 10^{7}Hz $ . What will be the frequency observed by an observer on the earth
[RPMT 1996]
Options:
A) $ 4\times 10^{6}Hz $
B) $ 3.2\times 10^{7}Hz $
C) $ 3\times 10^{6}Hz $
D) $ 5\times 10^{7}Hz $
Show Answer
Answer:
Correct Answer: B
Solution:
$ \nu ‘=\nu ( 1-\frac{v}{c} )=4\times 10^{7}( 1-\frac{0.2c}{c} )=3.2\times 10^{7}Hz $
