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A Young's double-slit experimental set up is kept in a medium of refractive index \(\left(\frac{4}{3}\right)\). Which ma…

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A Young's double-slit experimental set up is kept in a medium of refractive index \(\left(\frac{4}{3}\right)\). Which maximum in this case will coincide with the \({6}^{\text{th }}\) maximum obtained if the medium is replaced by air?

a

\({4}^{\mathrm{th}}\)

b

\({6}^{\text{th }}\)

c

\({8}^{\text{th }}\)

d

10th

✓ Correct answer: c)

\({8}^{\text{th }}\)

Explanation

For the \({6}^{th}\)Sv6Kpe[] maximum in air to coincide with the \({n}^{th}\)Sv6Kpe[] maximum in the medium, their fringe positions must be equal:Sv6Kpe[]

    Sv6Kpe[]

Sv6Kpe[]

\({y}_{6,air}=\frac{6{\lambda }_{air}D}{d}\) \({y}_{n,medium}=\frac{n{\lambda }_{medium}D}{d}=\frac{n(\frac{{\lambda }_{air}}{4/3})D}{d}\) Solving for \(n\)Sv6Kpe[]Sv6Kpe[]: Setting the two equations equal:Sv6Kpe[] \(\frac{6{\lambda }_{air}D}{d}=\frac{n(\frac{{\lambda }_{air}}{4/3})D}{d}\) \(6=\frac{n}{(4/3)}\) \(6=n\times \frac{3}{4}\) \(n=6\times \frac{4}{3}=8\)

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