CBSE Class 10 Answered

Place a rectangular glass slab on the white sheet of paper fixed on a drawing board.Trace the boundary ABCD of the glass slab.Remove the glass slab and draw a normal N1N2 at O.Draw a straight line IO inclined at an angle say 0  with the normal. IO is the incident ray.Fix two pins S and T on the incident ray IO.Place the glass slab within its boundary ABCD.Looking from the other side of the glass slab fix two other pins U and V such that S, T, U and V appear to lie on the same straight line.Remove the glass slab and the pins. Mark the pin points S, T, U and V.Join the pins U and V and produce the line on both sides. The ray O'E is the emergent ray.Join OO'. It is the refracted ray.The incident ray, the refracted ray and the normal are all lying in the same plane.This proves the first law of refraction