Optics Question 240
Question: A rocket is moving away from the earth at a speed of $ 6\times 10^{7}m/s $ . The rocket has blue light in it. What will be the wavelength of light recorded by an observer on the earth (wavelength of blue light = $ 4600{AA} $ )
Options:
A) $ 4600{AA} $
B) $ 5520{AA} $
C) $ 3680{AA} $
D) $ 3920{AA} $
Show Answer
Answer:
Correct Answer: B
Solution:
$ \frac{\Delta \lambda }{\lambda }=\frac{v}{c}=\frac{6\times 10^{7}}{3\times 10^{8}}=0.2 $
$ \Delta \lambda =\lambda ‘-\lambda =0.2\lambda \Rightarrow \lambda ‘=1.2\lambda =1.2\times 4600=5520{AA} $
