Optics Question 264
Question: The $ 6563{AA} $ line emitted by hydrogen atom in a star is found to be red shifted by $ 5{AA} $ . The speed with which the star is receding from the earth is
[Pb. PMT 2002]
Options:
A) 17.29 - 109 m/s
B) 4.29 - 107 m/s
C) 3.39 - 105 m/s
D) 2.29 - 105 m/s
Show Answer
Answer:
Correct Answer: D
Solution:
$ \frac{\Delta \lambda }{\lambda }=\frac{v}{c}\Rightarrow v=\frac{\Delta \lambda }{\lambda }.c $
$ =\frac{5}{6563}\times (3\times 10^{8})=2.29\times 10^{5} $ m/sec
