Q 12-08-038JEE MainJEE Main 2026 (28 Jan, Shift 1)Easy
The electric field of an electromagnetic wave travelling through a medium is given by
$\vec E(x,t) = 25\sin\left(2.0\times10^{15}t - 10^7x\right)\hat n$ then the refractive index of the medium is ______ .
(All given measurement are in SI units)
Answer: (C) 1.5
Speed of the wave in the medium:
$$v = \frac{\omega}{k} = \frac{2.0\times10^{15}}{10^7} = 2\times10^8\ \text{m/s}$$
$$n = \frac cv = \frac{3\times10^8}{2\times10^8} = 1.5$$
Solution by Sreeraj P, M.Sc Physics