Question

during refraction of light through the glass slab incident ray and emergent Ray are parallel to each other explain

Answer 1

When the incident ray enters the glass slab it bents towards the normal as glass slab is denser than air. And when the Rays enters air bents away from the normal and parallel to the incident ray.

Answer 2

during refraction of light through a glass slab incident ray and emergent ray are parallel to each other. the distance of displacement is known as lateral displacement.

let us consider a glass slab of abcd

a ray RP travelling through air be incident on the ab at point P. after refraction, it moves along PQ within the slab. On reaching the lower surface dc, it gets refracted again as it re enters to air

If refractive index of the glass slab is n, then

sin i/sin r=n              (applying Snell's law at interface ab)

sin i=n sin r    ......(i)

for the surface cd, PQ is the incident ray and QS is the refracted ray. Normals to ab and cd are parallel as ab II cd.

therefore, PQ makes angle r with normal at Q i.e., angle of incidence at Q =r. let the angle of refraction be r'

here, glass is the first medium and air is the second medium

therefore, sin r/sin r'=1/n    .........(ii)

or, sini= sin r'

therefore, i = r'

=> the ray QS is parallel to the ray RP

when a light ray passes through a transparent slab with parallel faces, the ray is displaced parallel to it self

hope it helps you ...sorry for the long content