Question

Light is incident normal to a liquid layer of refractive index 1.33 that lies on top of a flat flint glass. The light will take 3.73x10^-11 s of more time to traverse through these two layers than the same distance in air. Find the refractive index of flint glass if the widths of liquid and glass layers are 1.5cm and 1.0cm.

Answer 1

We know that light becomes slower in a medium. Therefore, the time it takes to travel in air is

$$t_1=(d_l+d_g)/c.$$

The time it takes to travel in the mediums is

$$t_2=(n_ld_l+n_gd_g)/c.$$

Therefore, the difference in time is

$$t=t_2-t_1.$$

The refractive index of glass is

$$n_g=\frac{ct-d_l(n_l-1)}{d_g}+1=1.52$$