BPSC 66th Prelims 27 Dec 2020 Paper

Concept:In a vacuum, all electromagnetic waves travel at a constant speed, which is the speed of light.Explanation:The speed of electromagnetic waves in free space is a fundamental constant, denoted by $c$.Its value is exactly $3 \times 10^{8}$ meters per second.This speed does not depend on frequency or wavelength.Among the given options, only $3 \times 10^{8} ms^{-1}$ is correct.Other values like $3 \times 10^{7}$ or $3 \times 10^{6}$ are incorrect.Answer:A. $3 \times 10^{8} ms^{-1}$