Q 12-10-112JEE MainJEE Main 2021 (18 Mar, Shift 2)Easy
A galaxy is moving away from the earth at a speed of 286 km s$^{-1}$. The shift in the wavelength of a red line at 630 nm is $x\times10^{-10}$ m. The value of $x$, to the nearest integer, is ______.
[Take the value of the speed of the light $c$, as $3\times10^8\ \text{m s}^{-1}$]
Numerical value type. Enter your answer.
Answer: 6
$$\Delta\lambda = \frac{v}{c}\lambda = \frac{286\times10^3}{3\times10^8}\times630\times10^{-9} \approx 6.0\times10^{-10}\ \text{m}$$
Solution by Sreeraj P, M.Sc Physics