A beam of light passing from one transparent medium to another obliquely, undergoes an abrupt change in direction. This phenomenon is known as refraction of light.
a. Name the law which satisfies during this refraction.
b. Draw the figure which shows refraction through a parallel sided glass slab. (Ray passing from air )
c. Using the figure obtaind in (b). Show that the incident ray and the emergent ray are parallel to each other.

Explanation

a. Snell.s law.
b.
c. Let ABCD be a rectangular refracting glass slab. PQRS is the course of ray through a parallel-sided glass slab placed in air.
Considering the refraction at face `AB, n = (sin i_(1))/(sin r_(1)) `
For refraction at face `DC, (1)/(n) = (sin r_(2))/(sin i_(2)) " therefore, " n = (sin i_(2))/(sin r_(2)) `
Hence `i_(1) = i_(2) and r_(1) = r_(2)`
We can see that the angle of incidence is equal to angle of emergence. Thus we can conclude that the emergent ray RS is parallel to incident ray. PQ , but is laterally displaced.