Refraction of waves
Refraction is the change in direction of a wave as it travels from one medium to another.
For instance, when light travels from air to glass or water waves travel from deep to shallow water.
When water waves pass from deep to shallow water they slow down because A force that opposes or prevents movement. When work is done against friction, kinetic energy is converted into heat energy. with the ripple tank base or seabed has greater impact in the shallow water.
As the waves slow down the waves bend towards the normal.
The frequency of the waves does not change because the source of the waves continues to vibrate at the same The number of waves produced each second. The unit of frequency is hertz (Hz)..
Since v = f\(\lambda\)
If the speed, v, decreases and the frequency, f, remains unchanged, then the The length of a single wave, measured from one wave peak to the next., \(\lambda\), must also decrease.
\(\lambda\)shallow is shorter than \(\lambda\) deep
Key point
FAST is a useful way of remembering the speed and direction changes of waves during refraction:
- If waves get Faster, they bend Away from the normal.
- If waves get Slower, they bend Towards the normal.
| Letter | Meaning |
| F | Faster |
| A | Away |
| S | Slower |
| T | Towards |
| Letter | F |
|---|---|
| Meaning | Faster |
| Letter | A |
|---|---|
| Meaning | Away |
| Letter | S |
|---|---|
| Meaning | Slower |
| Letter | T |
|---|---|
| Meaning | Towards |