Describe an activity to show refraction of light through a prism. Draw relevant figure, marking angle of incidence, refraction emergence, and deviation.

Explanation

To study refraction of light through a triangular glas prism :
(1) Fix a sheet of white paper on a drawing board using drawing pins.
(2) Place the glass prism on the board with its triangular base lying at the bottom. Trace the outline of the base using pencil.
(3) Fix two pins - P and Q - on a line as shown in the figure.
(4) Observe the image of P and Q through the face AC.
(5) Fix two more pins R and S such that they lie in the straight line containing images of P and Q.
(6) Remove the prism and the pins.
(7) Label the points where PQ and RS meet the boundary of the prism at E and F respectively. Join PE, EF and FS as shown.
(8) Draw perpendicular NN. and MM. to the faces AB and AC of the prism at points E and F respectively.
(9) Mark the angle of incidence `angle i`, angle of refraction `angle r` anad angle of emergence `angle e` as shown.

Inference : At face Ab, as the incident ray PE is travelling from rarer medium [air] to denser medium [glass], it is bent towards the normal NN. along EF. At face AC, ray EF gets refracted by travelling from denser to rarer medium. Hence, the emergent ray FS bends away from the normal, towrds the base of the prism. This is different from refraction in a glass slab because, the incidence ray is not parallel to the emergent ray as in the glass slab.