Fringe width: $\beta = \frac{\lambda D}{d}$
In liquid, $\lambda' = \frac{\lambda}{\mu}$
$$\beta' = \frac{\lambda' D}{d} = \frac{\lambda D}{\mu d} = \frac{\beta}{\mu}$$
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JEE Main 2020 — Physics Optics
medium
mcq
2020
Official previous-year question
Verified 30 May 2026.
Question
In Young's double slit experiment, the fringe width is $\beta$. If the entire arrangement is immersed in a liquid of refractive index $\mu$, the fringe width becomes:
Options
- A
$\frac{\beta}{\mu}$
- B
$\beta\mu$
- C
$\frac{\beta}{\mu^2}$
- D
$\beta\mu^2$
Solution
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