Light enters from air into water of refractive index (4)/(3). The percentage change in its wavelength is

Correct answer: A. 25\ \% The wavelength of light in a medium of refractive index μ is given by λ' = (λ)/(μ) , where λ is the wavelength in air. Given μ = (4)/(3) . λ' = (λ)/(4/3) = (3λ)/(4) Change in wavelength, Δ λ = λ - λ' = λ - (3λ)/(4) = (λ)/(4) Percentage change in wavelength = (Δ λ)/(λ) × 100 = (λ/4)/(λ) × 100 = 25\% Answer: 25\ \%

MHT CET 202622 AprilEvening Shift

Exam: MHT CET
Year: 2026
Date: 22 April
Shift: Evening Shift
Subject: Physics
Chapter: Ray Optics

MHT CET 2026 · 22 April · Evening Shift · Physics · Ray Optics

Light enters from air into water of refractive index (4)/(3). The...

Light enters from air into water of refractive index \dfrac{4}{3}. The percentage change in its wavelength is

Options

A $25\ \%$
B $50\ \%$
C $30\ \%$
D $20\ \%$

Correct answer

A. $25\ \%$

Step-by-step solution

The wavelength of light in a medium of refractive index

\mu

is given by

\lambda' = \dfrac{\lambda}{\mu}

, where

\lambda

is the wavelength in air.

Given

\mu = \dfrac{4}{3}

\lambda' = \dfrac{\lambda}{4/3} = \dfrac{3\lambda}{4}

Change in wavelength,

\Delta \lambda = \lambda - \lambda' = \lambda - \dfrac{3\lambda}{4} = \dfrac{\lambda}{4}

Percentage change in wavelength

= \dfrac{\Delta \lambda}{\lambda} \times 100 = \dfrac{\lambda/4}{\lambda} \times 100 = 25\%

Answer:

25\ \%

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