Question

Young's double-slit experiment is made in a liquid. The tenth bright fringe in liquid lies in screen where 6ht dark fringe lies in vacuum. The refractive index of the liquid is approximately

• A. $1.8$
• B. $1.54$
• C. $1.67$
• D. $1.2$

Answer 1

The correct option is A $1.8$

In liquid, wavelenth reduces by a factor equal to refractive index of liquid μ.

Path difference is equal for bright and dark condition

$\therefore 10\frac{\lambda }{\mu }=(2\times 6-1)\frac{\lambda }{2}$

$\mu =\frac{20}{11}=1.81$