Optics Question 843

Question: Young’s double slit experiment is made in a liquid. The 10th bright fringe lies in liquid where 6th dark fringe lies in vacuum. The refractive index of the liquid is approximately

Options:

A) 1.8

B) 1.5

C) 1.3

D) 1.6

Show Answer

Answer:

Correct Answer: A

Solution:

[a] Fringe width ω=λDd

When the apparatus is immersed in a liquid, then λ will decrease μ times and hence ω is reduced μ (refractive index) times.

10ω=(5.5)ω

or 10λ(Dd)=(5.5)λDd or λλ=105.5=μ

or μ=1.8



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