To Determine the refractive index of a glass slab using travelling microscope.

AIM:To Determine the refractive index of a glass slab using travelling microscope

APPARATUS REQUIRED:

A glass slab,a travelling microscope,and Lycopodium powder(fine chalk powder)

THEORY:

Due to the phenomenon of refraction of light through the glass slab ,there is variation in the real depth and apparent depth of the glass slab.The apparent depth  of the glass slab is less than the real depth of the glass slab.

The refractive index of the glass slab is given by

  Refractive index 

=Real Depth/Apparent depth

OBSERVATIONS:

Vernier constant of the travelling microscope is 0.001cm or 0.01mm.

Observation Table:

RESULT:

The refractive index of the material of the glass slab is 1.403

PRECAUTIONS:

1)The microscope should be carefully focussed.

2)The microscope screw should be moved only in one direction to avoid backlash error.

3)The powder should be spread on the top of the slab.

4)The particles used should be very fine and a thin layer should be formed.