Question

A ray of light is incident in water at an angle of

(i) 30 degree.

(ii) 70 degree on a water glass plane surface. Calculate the angle of refraction in the glass in each case. ( n of glass = 1.5 , n of water = 1.33)

Answer 1

(i) Let's write the Snell's Law:

$$n_isin\theta_i=n_rsin\theta_r,$$ $$\theta_r=sin^{-1}(\dfrac{n_isin\theta_i}{n_r}),$$ $$\theta_r=sin^{-1}(\dfrac{1.33\cdot sin30^{\circ}}{1.5})=26.3^{\circ}.$$

(ii) In case of angle of incidence $70^{\circ}$, we get:

$$\theta_r=sin^{-1}(\dfrac{1.33\cdot sin70^{\circ}}{1.5})=56.4^{\circ}.$$