How does a generator work?
A generator produces a voltage by electromagnetic induction — moving a coil in a magnetic field (or a magnet near a coil) induces a potential difference.
GCSE Physics
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In more detail
As the coil rotates in the magnetic field, it cuts through magnetic field lines, which induces a potential difference across the coil. The faster the rotation or the stronger the field, the larger the induced voltage. An alternator uses slip rings and produces alternating current (AC); a dynamo uses a split-ring commutator and produces direct current (DC).
Key points for the exam
- Induced voltage increases with a stronger magnet, more turns, or faster rotation.
- Alternator (slip rings) → AC; dynamo (split-ring commutator) → DC.
- It is the reverse of a motor: a motor uses current to make movement; a generator uses movement to make current.
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