Question

A two slit young's interference experiment is done with monochromatic light of wavelength $6000A^o$. the slits are $2mm$ apart. the fingers are observed on a screen placed $10cm$ away from the slits. now a transparent plate of thickness $0.5mm$ is placed in front of one of the slits and it is found that the interference pattern shifts by $5mm$. the refractive index of the transparent plate is

• A. $1.2$
• B. $0.6$
• C. $2.4$
• D. $1.5$

Answer 1

The correct option is A $1.2$

$\Delta x=(\mu -1)t\frac{D}{d}$

$5\times {10}^{-3}=(\mu -1)\times 0.5\times {10}^{-3}\times \frac{0.1}{2\times {10}^{-3}}$

$5=(\mu -1)25$

$\mu =\frac{1}{5}+1$

$=1.2$