Higher: refraction and radio waves

The idea

Refraction is the change in direction when a wave crosses a boundary between materials at an angle, because its speed changes. In a wavefront diagram, the part of the wavefront that enters the slower material first slows down first, so the wave bends towards the normal. Radio waves can be produced by oscillations in electrical circuits; when absorbed, they can create an alternating current with the same frequency in a receiver. Each type of wave suits its use because of how it is absorbed, transmitted or reflected.

1. Say whether the wave speeds up or slows down.
2. Use wavefronts to show which part changes speed first.
3. Link the property of the wave to its use.

Watch out A wave hitting a boundary along the normal changes speed but not direction.