Question

A ray of light is incident on a rectangular plate at an angle of incidence ${60}^o$. The light ray suffers a deviation which is 25% of the angle of incidence . The refractive index of the glass will be

• A. $\sqrt{3}$
• B. $\sqrt{2}$
• C. $\sqrt{\frac{3}{2}}$
• D. $1.5$

Answer 1

The correct option is C $\sqrt{\frac{3}{2}}$

Given,

$\delta =25\%ofi$

$=\frac{25}{100}\times 60={15}^0$

Then,

$r=60-15={45}^0$

By laws of refraction,

$\mu =\frac{sini}{sinr}$

That is,

${\mu }_2=\frac{sin60}{sin45}$

where, ${\mu }_2$ is the refractive index of glass.

${\mu }_2=\frac{\sqrt{3}/2}{1/\sqrt{2}}=\sqrt{\frac{3}{2}}$