Concept preview

What you will be able to do

1. 01Describe reflection, refraction and diffraction of waves
2. 02Explain interference and standing waves using superposition
3. 03Explain the Doppler effect

Once you know what a wave is, the fun is in what it does. Every wave — water, sound, light — can reflect (bounce off a barrier), refract (bend when its speed changes), diffract (spread around edges), interfere (combine with another wave), and produce the Doppler effect (shift in observed frequency when the source or the observer moves). These five behaviours explain everything from echoes and rainbows to why an ambulance siren drops as it races past.