Physics Question 103 – AP-EAMCET 2025

A source of light approaching the earth emits a light of wavelength 600 nm. If this light is observed at a wavelength of 599 nm by an observer on the earth, then the speed of the source of light in $km{s}^{-1}$ is (speed of light in vacuum $=3\times {10}^{8}m{s}^{-1}$)