DETERMINATION OF REFRACTIVE INDEX OF A MATERIAL

DETERMINATION OF REFRACTIVE INDEX OF A MATERIAL

Aim: To determine the refractive index of a material.

Apparatus: Refractometer, cynringe, tissue paper, beaker.

Reagent: Ethanol.

Sample: Any material.

Significant/Uses: is a character use to assess the purity of a substance.

Theory/Definition: the refractive index or index of refraction of a material is a dimensionless number that describes how light pass through that medium. It is defined as n = c/v,where c = speed of light in a vacuum, v = is the phase velocity of light in the medium.

It is defined as the ratio of the speed of light in vacuum(c = 299792458m/s), and the phase velocity (v) of the light in the medium. The phase velocity is the speed at which the crest or the phase of the wave moves, which may be different from the group velocity (the speed at which pulse of light or envelop of the wave moves.

Procedures for determination of refractive index of a substance

•          Switch on the equipment and leave it for 30 minutes for a bright light to come up.

•         Open the sample lid and clean it with ethanol using cotton wool, to remove impurity.

•         Insert the sample on the lid using synringe, and wipe with tissue paper to remove the ethanol.

•         Insert the sample on the lid using cynringe and closed it.

•         View from the upper eye piece while turning the knob until a light shadow divide the diagonal into two equal half.

•         View from the lower eye piece and record your reading from the scale.

•         View the screen and record the temperature reading.