When do waves travel at different speeds?
In substances which have different densities
What do EM waves travel more slowly in?
Denser media (usually)
What do sound waves travel faster in?
Denser substances
What happens when a wave crosses a boundary between two substances?
It changes speed
What happens if the wave hits the boundary ‘face on’?
It slows down but carries on in the same direction
When the wave changes direction it is said to have been?
Refracted
Look at the diagram page 32
Ok