Question

Prove that experimentally the emergent ray is parallel to the incident ray

Answer 1

in a glass slab:

*place a glass slab on a sheet of paper and draw the outline of it on the paper

*in an angle of say 50° (measured after drawing a normal to the side of the slab), draw a line and fix two pins at two points ON the line

this is the incident ray

*look at the pins from the other side of the glass slab and fix two pins in the direction (straight line) of the previous pins, as seen from the other side of th slab

*draw a normal for the line in which the latter pins are fixed

*measure the angle between the normal and the line of the pins

*it is observed that this angle is also 50°, which makes it parallel to the previous angle

this is the emergent ray

so, the incident ray || the emergent ray

hope it helps!!