Question

Verify laws of refraction using a glass slab

Answer 1

PROCEDURE:

a) Fix a sheet of white paper on the drawing board with the help of drawing

pins at the four corners of the sheet.

b) Place a glass slab at the centre of the paper and mark its boundary EFGH

with fine pencil.

c) Remove the glass slab. Draw any line AB making an angle of 400 with

the normal at the point B, the middle point of EF approximately.

d) Put the glass slab back in position on the boundary line. Fix two pins P1

and P2 vertically on the line AB at least 5cm apart- and one pin close to

the slab.

e) Look for the image of these pins in the slab from the opposite side GH

and fix two pins P3 and P4 so that they are in the line with the image of P1

and P2 as seen through the slab and at least 5cm apart.

f) Join the pricks of P3 and P4 to obtain the emergent ray. Draw a normal to

GH at the point C. join BC to get the refracted ray.

g) Measure the angle of incidence and angle of refraction. Produce AB

forward and draw a perpendicular from C on AB produced to meet it at P.

Then the lateral displacement = CP.

h) Repeat the experiment with different angles of incidence 500

and 600