IGCSE Physics: Electromagnetic Induction and Generators | Magnetism & Electromagnetism | Unit 7 | L7

This lesson covers spec points 7.15 and 7.16 of the Edexcel Modular IGCSE Physics specification — electromagnetic induction, the factors that
affect the induced voltage, why parallel motion produces no induction, and the structure and
output of AC and DC generators.

PowerPoint includes:
• Retrieval starter reviewing the motor effect and the link between current and magnetism
• Direct Instruction (I Do) — electromagnetic induction introduced as the reverse of the
motor effect; relative motion between a conductor and magnetic field established as the
cause; three factors affecting induced voltage explained (speed of movement, field strength,
number of turns); why parallel motion gives zero voltage explained using field line cutting;
AC generator structure introduced (coil, slip rings, brushes, permanent magnets); how
induced voltage varies through one full rotation explained with reference to the voltage–
angle graph; DC generator contrasted (split-ring commutator gives pulsed DC); updated
slide on dynamos clarifying that bicycle dynamos are alternators (AC), not DC generators
• Guided Practice (We Do) — three questions: explain why moving a magnet into a coil
more quickly produces a greater voltage; sketch the output waveform of an AC generator;
describe what happens when the magnet is held stationary inside the coil
• Check for Understanding — 4 MCQs including a true/false on whether DC can be used in
transformers; answers on following slides
• Independent Practice (You Do) — activity sheet with exam-style questions
• Review and Reflect — exit ticket: what would happen if the National Grid used DC?

Activity Sheet includes:
• 10 questions covering electromagnetic induction from first principles, factors affecting
induced voltage, the generator effect and differences between AC and DC generators
• Q10 — 4-mark extended answer: describe how an AC generator produces electricity (a
classic IGCSE exam question requiring students to link coil rotation, field line cutting,
induced voltage and alternating current)
• Stretch question: a magnet is moved into a coil, held still, then removed — describe and
explain the ammeter reading at each stage (25 marks total)
• Note: “induced voltage” used throughout in place of “EMF” for IGCSE-appropriate language
• Full mark scheme for teacher use