Question

A laser travels from glass to water at an angle of 35° with the normal, Θ1. If water has an index of refraction of 1.33 and glass has an index of refraction of 1.52, determine Θ2. A) 30.1° B) 41.0° C) 50.2° D) 57.0°

Answer 1

When light moves from one medium to another, it is refracted. If it moves from a medium with refractive index n1 to one with refractive index n2, with an incidence angle to the surface normal of θ1, the refraction angle θ2 can be calculated from Snell's law.

The Snell's law states that the ratio of the sines of the angles of incidence and refraction of a wave (in this case beam/light) are constant when it passes between two given media.

$n_1\sin\theta_1=n_2\sin\theta_2$

Given that a laser travels from glass to water at an angle of 35° with the normal, $\theta_1$. If water has an index of refraction of 1.33 and glass has an index of refraction of 1.52, then we have:

$1.52\sin35^o=1.33\sin\theta_2 \\ \\ \Rightarrow\sin\theta_2= \frac{1.52\sin35^o}{1.33} =0.6555\therefore\theta_2=\sin^{-1}0.6555\approx41^o$