JEE Main 2026 Jan 22 Shift 2, Physics Q12: Introduction

JEE Main2026Jan 22, Shift 2Physics

The wavelength of light, while it is passing through water is 540 nm. The refractive index of water is $\frac{4}{3}$ . The wavelength of the same light when it is passing through a transparent medium having refractive index of $\frac{3}{2}$ is _____ nm.

A
380
B
840
C
480
D
540

Solution

Frequency stays constant across media, so $μ λ$ is constant.

$μ_{1} λ_{1} = μ_{2} λ_{2} \Rightarrow \frac{4}{3} (540) = \frac{3}{2} λ_{2}$ .

$λ_{2} = \frac{4 \times 540 \times 2}{3 \times 3} = \frac{4320}{9} = 480$ nm.

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