Waves is a core part of GCSE Physics. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Transverse & longitudinal wavesVibrations perpendicular (light) or parallel (sound) to travel.
Frequency & wavelengthNumber of waves per second and the length of one wave.
Wave speedv = f × λ, the speed a wave travels.
AmplitudeMaximum displacement from the rest position; relates to energy.
Electromagnetic spectrumRadio to gamma; all travel at the speed of light in a vacuum.
Reflection & refractionWaves bounce off surfaces or change direction when changing medium.
RefractionLight changing direction as it enters a new medium
Optically denserMedium in which light travels more slowly
Refractive indexHow much a medium slows light compared to vacuum
Converging lensA lens that bends parallel rays to a focal point
Diverging lensA lens that spreads parallel rays apart
Focal lengthDistance from the lens to its focal point, in metres
DispersionSplitting white light into its colours by a prism
SpectrumThe band of colours from red through violet
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
When a wave travels through water, what happens to the water itself?✗ The water moves along with the wave from one place to another. ✓ The water oscillates about a fixed point; the wave transfers energy, not matter.
How do you see a non-luminous object like a book?✗ Your eyes send out beams of vision that hit the book and let you see it. ✓ Light from a source reflects off the book and enters your eyes.
What property of a sound wave determines its pitch?✗ Amplitude determines pitch — a bigger wave is a higher-pitched note. ✓ The frequency — higher frequency means higher pitch.
When a water wave moves from deep into shallow water, what happens?✗ Speed and wavelength both increase ✓ Speed decreases and wavelength decreases, frequency stays the same
Why does light bend when it enters a denser medium like glass?✗ Because the medium is denser, it physically blocks part of the light and forces it to turn. ✓ Because it slows down — the change in speed at the boundary causes the wavefront to bend (towards the normal).
Practise Waves — free games
Test yourself with these quick revision games for this topic:
See all 17 games in the Subjects Arcade →
More GCSE Physics topics
← All revision guides
Want to revise every topic this smart?
The Velvet Method teaches you to use AI to revise any subject — £25, lifetime access.
Explore the Course →