Question

The wavelength of light received from a galaxy is 10% greater than the received from an identical source on the earth. The velocity of the galaxy relative to the earth is

• A. $3\times {10}^{6}m{s}^{-1}$
• B. $3\times {10}^{5}m{s}^{-1}$
• C. $3\times {10}^{8}m{s}^{-1}$
• D. $3\times {10}^{7}m{s}^{-1}$

Answer 1

The correct option is D $3\times {10}^{7}m{s}^{-1}$

$v=\frac{\Delta \lambda }{\lambda }c$

Here we are given, $\frac{\Delta \lambda }{\lambda }=0.1$, and $c=3.0\times {10}^{8}m{s}^{-1}$,

$\Rightarrow v=3.0\times {10}^{7}m{s}^{-1}$