Generators and Dynamos

This lesson covers AC and DC generators, including how they produce electricity and the characteristics of their output — as required by the Edexcel GCSE Physics specification (1PH0), Topic 8: Magnetism and Electromagnetism. You need to understand how generators work, the difference between AC and DC generators, and how to interpret voltage–time graphs.

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The AC Generator (Alternator)

An AC generator (also called an alternator) converts kinetic energy into electrical energy by electromagnetic induction. It produces alternating current (AC) — the current repeatedly reverses direction.

Components of an AC Generator

Component	Function
Rectangular coil	Rotates in the magnetic field; the conductor in which voltage is induced
Permanent magnets	Provide a steady magnetic field (N and S poles facing each other)
Slip rings	Two continuous rings attached to the coil; rotate with the coil
Carbon brushes	Stationary contacts that press against the slip rings; connect the coil to the external circuit
Axle	The coil rotates around this central axis

How the AC Generator Works