Question

As shown in the figure, in Young's double slit experiment, a thin plate of thickness $t=10\mu m$ and refractive index $\mu =1.2$ is inserted infront of slit $S_1$. The experiment is conducted in air $(\mu -1)$ and uses a monochromatic light of wavelength $\lambda =500nm$. Due to the insertion of the plate, central maxima is shifted by a distance of $x{\beta }_0.{\beta }_0$ is the fringe-width befor the insertion of the plate. The value of the $x$ is ___

Answer 1

Answer: 4

Fringe shift $=\frac{t(\mu -1)}{\lambda }B$
$=\frac{10\times 10^{-6}(1.2-1)}{5\times 10^{-7}}B$
$=\frac{10^{-5}\times 0.2}{5\times 10^{-7}}=4$