Physics practical

Refraction through a glass block

Shine a ray into a glass block at five or more angles, measure the angles of refraction, and find the refractive index from a graph.

What you will do

1. 01Place the glass block on the paper and aim the ray box at the middle of its long face.
2. 02Turn the ray box to set an angle of incidence i, measured from the normal.
3. 03Read the angle of refraction r inside the block with the protractor, centred where the ray enters.
4. 04Repeat for at least five angles from about 20° to 70°.
5. 05Calculate sin i and sin r, plot sin i against sin r, and find the gradient: the refractive index.