State the laws of refraction. Explain the phenomenon of refraction when a ray of light passes through a rectangular glass slab with the help of a ray diagram.

(N/A) The laws of refraction are as follows:
$1$. The incident ray, the refracted ray, and the normal to the interface of two transparent media at the point of incidence all lie in the same plane.
$2$. Snell's Law: The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for the light of a given color and for a given pair of media, expressed as $\frac{\sin i}{\sin r} = \text{constant} = n_{21}$.
When a light ray passes through a rectangular glass slab:
- The ray enters from air to glass (denser medium) and bends towards the normal.
- It travels through the glass and exits from glass to air (rarer medium), bending away from the normal.
- The emergent ray is parallel to the incident ray but laterally displaced. This perpendicular distance between the original path of the incident ray and the emergent ray is called lateral displacement.