Snell’s Law of Refraction

Light changes speed when it passes from one transparent medium to another, so it bends at the boundary. Drag the angle of incidence, pick the two media, and compare the angle of refraction with the value Snell’s law predicts.

What you will learn

See how a ray bends between two media, measure sin i / sin r, and find when total internal reflection happens.

How to use it

1. Drag the angle slider to change the angle of incidence.
2. Choose different media for the upper and lower half.
3. Look at sin i / sin r: it stays the same for the same pair of media.
4. Send light from glass into air and raise the angle past the critical angle to see total internal reflection.