All Problems

Interference of Light

Problem 5.76

A plane monochromatic light wave falls normally on a diaphragm with two narrow slits separated by a distance \(d=2.5 \mathrm{~mm}\). A fringe pattern is formed on a screen placed at a distance \(l=\) \(=100 \mathrm{~cm}\) behind the diaphragm. By what distance and in which direction will these fringes be displaced when one of the slits is covered by a glass plate of thickness \(h=10 \mu \mathrm{m} ?\)

Reveal Answer
5.76. The fringes are displaced toward the covered slit over the  distance Δx=hl(n1)/d=2.0 mm\begin{aligned} &5.76 . \text { The fringes are displaced toward the covered slit over the }\\ &\text { distance } \Delta x=h l(n-1) / d=2.0 \mathrm{~mm} \end{aligned}