To Verify Snell's Law of Refraction

Apparatus

Raybox, semi-circular Perspex block, protractor.

Method

Set up apparatus as in diagram.

Record i, the angle of incidence, and r, the angle of refraction. Measure these angles from the normal.

Repeat for different values of i and r.

Graph sin i against sin r.

A straight line graph through the origin verifies Snell’s law.

Sources of Error

Too small an angle of incidence leads to a high percentage error as the protractor is only accurate to the nearest degree.

Solution

Ensure that the smallest value of i is 20^o.