Pearson Edexcel International GCSE in Physics · 4PH1 · Free · no account needed
Topic 3 · Waves
What a wave is and what it carries, the wave equation, the Doppler effect, the whole electromagnetic spectrum with its uses and dangers, reflection, refraction, total internal reflection and sound.
Every lesson here ends the same way: learn it, teach it to an AI pupil who asks the awkward question, then defend it against the thinker with the strongest claim on it — free · no account needed.
10 lessons, covering 29 specification statements.
What you need to know — the 29 statements, and where each one is taught
Every statement this topic carries, in the specification's own numbering, with Incandio's restatement of what it asks and the lesson that discharges it. Tick them off against your own copy of the specification: this is the topic's revision checklist, not a summary of it. Incandio is aligned to this specification. It is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording — the statement numbers are given so you can check every lesson against your own copy.
| Statement | What it asks | Taught in |
|---|---|---|
| 3.1 | Use the units degree, hertz, metre, metre/second and second | What a Wave Is |
| 3.2 | The difference between longitudinal and transverse waves | What a Wave Is |
| 3.3 | Definitions of amplitude, wavefront, frequency, wavelength and period | What a Wave Is |
| 3.4 | Waves transfer energy and information without transferring matter | What a Wave Is |
| 3.5 | Use v = f × λ | The Wave Equation |
| 3.6 | Use f = 1 ÷ T | The Wave Equation |
| 3.7 | Use those relationships in different contexts, including sound and electromagnetic waves | The Wave Equation |
| 3.8 | The Doppler effect: why observed frequency and wavelength change when the source moves | The Doppler Effect |
| 3.9 | All waves can be reflected and refracted | The Doppler Effect |
| 3.10 | Light as part of a continuous electromagnetic spectrum, all travelling at the same speed in free space | The Electromagnetic Spectrum |
| 3.11 | The order of the electromagnetic spectrum, including the colours of the visible spectrum | The Electromagnetic Spectrum |
| 3.12 | Uses of each electromagnetic radiation | Uses and Dangers of Electromagnetic Radiation |
| 3.13 | Detrimental effects of excessive exposure to electromagnetic waves, and protective measures | Uses and Dangers of Electromagnetic Radiation |
| 3.14 | Light waves as transverse waves that can be reflected and refracted | Reflection and Ray Diagrams |
| 3.15 | Use the law of reflection | Reflection and Ray Diagrams |
| 3.16 | Draw ray diagrams to illustrate reflection and refraction | Reflection and Ray Diagrams |
| 3.17 (practical) | Practical: investigate the refraction of light using rectangular, semi-circular and triangular blocks | Refraction and Refractive Index |
| 3.18 | Use n = sin i ÷ sin r | Refraction and Refractive Index |
| 3.19 (practical) | Practical: investigate the refractive index of glass using a glass block | Refraction and Refractive Index |
| 3.20 | The role of total internal reflection in optical fibres and prisms | Total Internal Reflection |
| 3.21 | The meaning of critical angle | Total Internal Reflection |
| 3.22 | Use sin c = 1 ÷ n | Total Internal Reflection |
| 3.23 | Sound waves as longitudinal waves that can be reflected and refracted | Sound Waves |
| 3.24 | The frequency range for human hearing | Sound Waves |
| 3.25 (practical) | Practical: investigate the speed of sound in air | Sound Waves |
| 3.26 | How an oscilloscope and microphone display a sound wave | Oscilloscopes, Pitch and Loudness |
| 3.27 (practical) | Practical: investigate the frequency of a sound wave using an oscilloscope | Oscilloscopes, Pitch and Loudness |
| 3.28 | How the pitch of a sound relates to the frequency of vibration | Oscilloscopes, Pitch and Loudness |
| 3.29 | How the loudness of a sound relates to the amplitude of vibration | Oscilloscopes, Pitch and Loudness |
The lessons
- What a Wave Is — Something crosses the room and nothing gets to the other side — the idea that makes the rest of the topic possible. (3.1, 3.2, 3.3, 3.4)
- The Wave Equation — Two equations that connect everything on the previous page — and one of them you could have worked out yourself. (3.5, 3.6, 3.7)
- The Doppler Effect — Why an ambulance changes note as it passes — and why the siren itself never does. (3.8, 3.9)
- The Electromagnetic Spectrum — Seven names for one thing — and the two properties that change as you go along it. (3.10, 3.11)
- Uses and Dangers of Electromagnetic Radiation — Seven bands, seven jobs — and why the danger rises steadily as you move along the spectrum. (3.12, 3.13)
- Reflection and Ray Diagrams — One rule, drawn correctly — and why the image in a mirror is behind it. (3.14, 3.15, 3.16)
- Refraction and Refractive Index — Why light bends entering glass, why it sometimes does not, and how to put a number on it. (3.17, 3.18, 3.19)
- Total Internal Reflection — The angle beyond which light cannot get out at all — and the technology built on it. (3.20, 3.21, 3.22)
- Sound Waves — What is actually travelling when you hear something, what you can and cannot hear, and how to measure how fast it goes. (3.23, 3.24, 3.25)
- Oscilloscopes, Pitch and Loudness — Seeing a sound on a screen — and which feature of the trace corresponds to which thing you hear. (3.26, 3.27, 3.28, 3.29)