To Verify Snell's Law And, Hence,
To Find A Value For The Refractive Index of Glass

In an experiment to verify Snell’s law, a ray of light was shone through a glass block and the following results obtained.

i / ^o	20	30	40	50	60	70
r / ^o	13	19	25	31	35	39

(i) Show, using a suitable graph, how the data verifies Snell’s law.

(ii) Use your graph to obtain a value for the refractive index of glass.

SOLUTION

Sin i	0.34	0.50	0.64	0.77	0.87	0.94
Sin r	0.22	0.33	0.42	0.52	0.57	0.63

(i) A straight line graph through the origin shows that sin i is proportional to sin r.
This verifies Snell’s law.

(ii)