Topic 4: Electricity & Magnetism

Magnets are fascinating — invisible forces that attract and repel. Permanent magnets, magnetic materials (iron, steel, nickel, cobalt), drawing magnetic field lines, the difference between hard and soft magnetic materials, and building electromagnets.

Understanding what's actually happening inside a circuit. Electric charge, current as the flow of charge (I = Q/t), electromotive force (e.m.f.) and potential difference, resistance and Ohm's law (V = IR), and reading I-V characteristic graphs for different components.

How to build circuits and predict what they'll do — a really practical topic! Series vs parallel circuits, current and voltage rules, combined resistance, potential dividers, thermistors and LDRs (sensors that react to temperature and light), diodes, LEDs, and logic gates.

Electricity is useful but can be deadly — knowing how to stay safe matters. Fuses and circuit breakers, why earthing protects you, double insulation, the three wires (live, neutral, earth) and their colours, power calculations (P = IV), energy (E = Pt), and the real dangers of electricity.

Where electricity and magnetism come together — this is how we generate power and make motors work. Electromagnetic induction, generators (a.c. and d.c.), transformers (Vₚ/Vₛ = Nₚ/Nₛ), the motor effect, Fleming's left-hand rule, d.c. motors, and loudspeakers.