Ray Optics

JEE Main level, single correct, medium

90 of 295

Question 90 of 295

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: The phase difference of two light waves change if they travel through different media having same thickness, but different indices of refraction.

Reason R: The wavelengths of waves are different in different media.

In the light of the above statements, choose the most appropriate answer from the options given below

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Answer: (D) Both A and R are correct and R is the correct explanation of A

When light travels through a medium, its velocity depends on the density of the medium.
The formula to calculate the speed of light can be written as

v=νλ...(1)v=\nu \lambda ...(1)
From equation (1), it can be concluded that higher the speed, higher is the wavelength. Hence, the wavelength of light depends on the refractive index of the medium.

Because of changed wavelength the phase difference changes while the two waves travel the same distance.

Thus, both A and R are correct and R is the correct explanation of A.

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