Optics Question 475

Question: In a YDSE light of wavelength λ=5000

Ao is used which emerges in phase from two slits a distance d=3×107m apart. A transparent sheet of thickness t=1.5×107m , is refractive index n = 1.17, is placed over one of the slits. Where does the central maxima of the interference now appear?

Options:

A) D(μ1)t2d

B) 2D(μ1)td

C) D(μ+1)td

D) D(μ1)td

Show Answer

Answer:

Correct Answer: D

Solution:

[d] The path difference introduced due to introduction of transparent sheet is given by

Δx=(m1)t.

If the central maxima occupies position of nth fringe, then (μ1)t=nλ=dsinθ

sinθ=(μ1)td=(1.171)×1.5×1073×107=0.085

Hence the angular position of central maxima is θ=sin1(0.085)=4.88

For small angles sinθθtanθ

tanθ=yD

yD=(μ1)td Shift of central maxima is y=D(μ1)td

This formula can be used if D is given.



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