Ray Optics

JEE Main level, single correct, medium

76 of 295

Question 76 of 295

The wavelength of light, while it is passing through water is 540 nm. The refractive index of water is 4/34 / 3. The wavelength of the same light when it is passing through a transparent medium having refractive index of 3/23 / 2 is ____\_\_\_\_ nm.

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Answer: (B) 480

Frequency of light is constant in all media.
In water with refractive index 4/34/3, wavelength is 540 nm.
The wavelength in vacuum is λ0=540×43=720\lambda_0 = 540 \times \frac{4}{3} = 720 nm.
In a medium with refractive index 3/23/2, the wavelength is λ=7203/2=720×23=480\lambda = \frac{720}{3/2} = 720 \times \frac{2}{3} = 480 nm.

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