Question

The bi-prism having an acute angle of $1^o$ and refractive index of $1.5$ is used in the interference experiment to produce two virtual slits from a single slit which is $5cm$ away from it and the screen is placed at $0.75m$ away from the bi-prism. Calculate the fringe width (in $\mu$m) if the slit is illuminated by light of $550nm$ wavelength

Answer 1

$y_1=0.05m,y_2=0.75m,\alpha =1^{\circ }$

D = $y_1+y_2=0.05+.75=0.8m$

$\lambda =550nm$

d = $2(\mu -1)\ast \alpha \ast y_1$ = $2\ast 0.5\ast \left(pi/180\right)\ast 0.05$

$\beta =\lambda \ast D/d$

=> $\beta =504\mu m$

Answer. Fringe width $\beta =504\mu m$