Physical Science / Unit 10: Electricity and Magnetism
10.7 Motors and Generators
Notes
- An electric motor changes electrical energy into mechanical energy. A current-carrying wire in a magnetic field feels a force, which spins a coil.
- A generator changes mechanical energy into electrical energy using electromagnetic induction: moving a wire through a magnetic field (or a magnet near a coil) induces a current.
- A transformer changes voltage in AC. Step-up increases voltage, step-down decreases it. Transformers need AC and work only if the number of turns differs.
- Power plants use turbines (turned by steam, wind or water) to spin generators.
Practice
What energy change occurs in an electric motor?
Motors use current to produce motion.
What does a generator do?
Spinning a coil in a magnetic field induces current.
Which action will induce a current in a coil of wire?
A changing magnetic field induces a current.
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