Question

Explain the refraction of light through a triangular glass prism
using a labelled ray diagram. Hence define the angle of deviation.

Answer 1

$\bullet$ABC is prism with base BC

$\bullet$ PE is incident ray on surface AB. It makes $\angle PEN$
with the normal NE. This angle is angle of incidence.

$\bullet$After entering the prism, the light ray bends towards normal.
In this case, EF is refracted ray. $\angle N^{\prime }EF$ is angle of refraction.

$\bullet$Once the refracted ray emerges from prism into air, it bends away from normal. In this figure, FS is emergent ray, $\angle SFM$ is angle of emergence.

Angle of Deviation: The angle between incident ray and emergent
ray is called angle of deviation. Here, $\angle SGH$ is angle of deviation or $\angle D$