The electric field of an electromagnetic wave travelling through a medium is given by
$\vec{E}$ (x,t) = 25 sin(2.0 × 10¹⁵t - 10⁷x) n̂
then the refractive index of the medium i $s ______.$
(All given measurements are in SI units)
Options

Question

The electric field of an electromagnetic wave travelling through a medium is given by

$\vec{E}$ (x,t) = 25 sin(2.0 × 10¹⁵t - 10⁷x) n̂

then the refractive index of the medium i $s ______.$

(All given measurements are in SI units)

Options

G1 Physics · Accepted Answer

Compare the wave with E⃗ = E₀ sin(ωt-kx)n̂. Therefore, ω = 2.0×10¹⁵ rad/s, k = 10⁷ m⁻¹. Wave speed in the medium is v = ω/k = (2.0×10¹⁵)/(10⁷) = 2.0×10⁸ m/s. The refractive index is μ = c/v. Using c = 3×10⁸ m/s, μ = (3×10⁸)/(2×10⁸) = 1.5. Correct option: C.

The electric field of an electromagnetic wave travelling through a medium is given by E ⃗ \vec{E} E (x,t) = 25 sin(2.0 × 10¹⁵t - 10⁷x) n̂ then the refractive index of the medium i s ______. (All given measurements are in SI units)