REFRACTION AT PLANE SURFACES EXPERIMENT

TITTLE : REFRACTION AT PLANE SURFACES EXPERIMENT

Apparatus : Rectangle glass block, glass prism, 4 optical pins, wooden board and paper

Aim ; to verify the laws of refraction and to determine the refractive index of glass

THEORY OF REFRACTION AT PLANE SURFACES EXPERIMENT;

When light passes from one medium to another, the ratio of the sine of angle of incident(I) to the sine of the angle of reflection(R) is a constant for a given pair of media.

This constant is called the refractive index U2 of the second medium with respect to the first.

If light travels from a less dense medium, the light is refracted towards the normal and U2 is greater than unity.

PROCEDURE OF REFRACTION AT PLANE SURFACES EXPERIMENT:

A rectangle glass block ABCD was placed on a sheet of paper and the position of the longer Faces AB and CD with a sharp pencil, arrange two pins P and Q about 10cm. place the other two pins R and S on the other side of the glass block so that when viewed horizontally through the glass, the four pin appears to be straight line. Remove the block, join PQ to meet AB at X and RS to meet CD at Y the rays of either side of the glass may be treated as incident rays.

AUG=SIN(i)/SIN(r)

AUG = SIN I / SIN r =1/sini/sinr=1/gua

The ratio of the sine of the angles was obtained by drawing a large circle with center X. the points where the incident and refracted rays cut the circle and from there drop perpendiculars LN and OT to the normal. Then

SIN i = LN/LX

SIN r = OT/TX

Aug = Sini/Sin r =LN/OT (because LX=XT)

The procedure was repeated for angles of incidence varying from about 10 to 63 degrees. At least five degrees were taken.

A table was drawn, showing the values of Sin I, sin R, sin E,AUG,GUA. The average value of both refractive indices was calculated, verifying that AIG * GIA = 1. A graph of sin I against sin r was plotted and the refractive index was calculated from the slope of the graph.