Optics Question 253
Question: Light coming from a star is observed to have a wavelength of 3737 Å, while its real wavelength is 3700 Å. The speed of the star relative to the earth is
[Speed of light $ 3\times 10^{8}m/s $ ] [MP PET 1997]
Options:
A) $ 3\times 10^{5}m/s $
B) $ 3\times 10^{6}m/s $
C) $ 3.7\times 10^{7}m/s $
D) $ 3.7\times 10^{6}m/s $
Show Answer
Answer:
Correct Answer: B
Solution:
$ \Delta \lambda =\lambda \frac{v}{c} $
$ \Rightarrow (3737-3700)=3700\times \frac{v}{3\times 10^{8}}\Rightarrow v=3\times 10^{6}m/s $
