The thickness of a plate having refractive index $\mu$ which will produce a change in optical path equal to…
The thickness of a plate having refractive index $\mu$ which will produce a change in optical path equal to half the wavelength $\lambda$ of the light passing through it is
$\frac{\lambda}{4(\mu-1)}$
$\frac{\lambda}{(\mu-1)}$
$\frac{3 \lambda}{4(\mu-1)}$
$\frac{\lambda}{2(\mu-1)}$
Solution
Let, $t=$ thickness of plate
Given, optical path difference $=(\mu-1) t=\lambda / 2$
$\Rightarrow t=\frac{\lambda}{2(\mu-1)}$
.