A plane electromagnetic wave is incident on a dielectric medium with refractive index n = 1.5. What is the ratio of the speed of the wave in the medium to the speed in vacuum?

B. 0.67 — The refractive index of a medium is defined as the ratio of the speed of light in vacuum to the speed of light in the medium. Therefore, the ratio of the speed in the medium to the speed in vacuum is the reciprocal of the refractive index.

JEE Main · PhysicsHard

$A plane electromagnetic wave is incident on a dielectric medium with refractive index . What is the ratio of the speed of the wave in the medium to the speed in vacuum ?$

A. $0.5$
B. $0.67$
C. $1.5$
D. $2.25$

Show correct answer & step-by-step solution

Correct answer: B — $0.67$

Solution

n = c / v ⟹ v / c = 1/ n = 1/1.5 = 2/3 \approx 0.67 .

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A plane electromagnetic wave is incident on a dielectric medium with refractive index n=1.5. What is the ratio of the speed of the wave in the medium v to the speed in vacuum c?

Solution

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More Electromagnetic Waves practice questions

$A plane electromagnetic wave is incident on a dielectric medium with refractive index . What is the ratio of the speed of the wave in the medium to the speed in vacuum ?$