Faraday’s Law

Electricity from motion

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• A changing magnetic flux induces a voltage (Faraday, 1831).
• $\mathcal{E} = -N\,\Delta\Phi/\Delta t$: faster changes and more turns give more voltage.
• Lenz’s law: induced currents oppose the change that made them.

Steps

1. A still magnet
2. Push the magnet through
3. Faraday’s law
4. More voltage
5. A coil’s voltage
6. The slow magnet
7. A magnet in a copper pipe