Young's double slit experiment is performed in water, instead of air, then fringe width

Young's double slit experiment is performed in water, instead of air, then fringe width
  1. decreases.
  2. becomes infinite.
  3. increases.
  4. remains same.

Solution

$\mathrm{X}=\frac{\lambda \mathrm{D}}{\mathrm{d}}$ In water the wavelength $\lambda$ decreases and hence the fringe width decrease.

Asked in: MHT CET 2020 (19 Oct Shift 1)

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