# Refraction

What would you predict would happen when a ray of light enters and then leaves a glass block?

I would predict that the following things would happen::
(a) as it entered the block the ray of light would slow down, its wavelength would decrease and if it entered the block at an angle it would refract, bending towards the normal (a line at ninety degrees to the block)
(b) it would then travel across the block in a straight line at a steady speed (less than its speed in air)
(c) as it left the block the ray of light would speed up to the same speed that it had before it entered the block, its wavelength would increase and if it left the block at an angle it would refract, bending away the normal so that it was travelling in the same direction as it was before it entered the block but shifted sideways

### schoolphysics Snell's Law interactive experiment

To see an interactive experiment to investigate Snell's law click on the animation link.

For more details of refraction see: Refraction (11-14)