CBSE Class 10 Science 2019 · Paper 31/2/1 · Question 26(a)

Diagram (see the figure): the incident ray strikes the upper face of the slab at an angle of incidence of about $45^{\circ }$ and bends towards the normal inside the glass; at the lower face it bends away from the normal as it passes into air. The emergent ray is parallel to the incident ray. (i) Angle of refraction $\angle r$: the angle between the refracted ray inside the slab and the normal at the point of incidence. (ii) Angle of emergence $\angle e$: the angle between the emergent ray and the normal at the point of emergence ($\angle e=\angle i$). (iii) Lateral displacement: the perpendicular distance between the emergent ray and the incident ray produced (drawn dashed).