Physics - Wave Optics Question with Solution | TestHub

The optical path length of light traveling through a medium of thickness $t$ and refractive index $\mu$ is $\mu t$.

The optical path length of light traveling the same distance in a vacuum is $t$.

The change in optical path produced by the plate is $\Delta x=\mu t-t=(\mu -1)t$.

Given that the change in optical path is equal to half the wavelength $\lambda$, we have:

$(\mu -1)t=\frac{\lambda }{2}$

$t=\frac{\lambda }{2(\mu -1)}$

Answer: $\frac{\lambda }{2(\mu -1)}$