1. Tardigrade
  2. Question
  3. Physics
  4. A plane monochromatic light falls normally on a diaphragm with two narrow slits separated by a distance d=2.5 mm. A fringe pattern is formed on the screen placed at D=100 cm behind the diaphragm. If one of the slits is covered by a glass plate of thickness 10 μ m, then distance by which these fringes will be shifted will be :

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Q. A plane monochromatic light falls normally on a diaphragm with two narrow slits separated by a distance $d=2.5 \, mm$. A fringe pattern is formed on the screen placed at $D=100\, cm$ behind the diaphragm. If one of the slits is covered by a glass plate of thickness $10\, \mu m$, then distance by which these fringes will be shifted will be :

Wave Optics

Solution:

If shift of fringes is $x$ then we use
$\frac{x d}{D}=(\mu-1) t$
$\Rightarrow x=\frac{(\mu-1) t D}{d}$
$\Rightarrow x=\frac{(1.5-1) \times 10^{-3} \times 100}{0.25}=0.2\, cm$