Physics - Wave Optics Question with Solution | TestHub

When a transparent plate of refractive index $\mu$ and thickness $t$ is introduced in the path of light from one of the slits in Young's double slit experiment, the optical path of that beam increases by $(\mu -1)t$.

This introduces an additional path difference between the interfering waves. For the central maximum, the net path difference must be zero. To compensate for the extra optical path introduced by the plate, the geometric path from the other slit must be greater.

As a result, the entire interference pattern, including the central maximum, shifts towards the side of the slit in front of which the plate is placed.

The fringe width $\beta =\frac{\lambda D}{d}$ depends only on the wavelength, slit separation, and screen distance, so it remains unchanged. The interference pattern does not disappear, and the number of fringes remains the same.

Answer: the central maximum will shift towards this side