Physics 12 · Physics · Lesson 7.2
Induction
- Level
- Grade 12
- Reading time
- 12 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
Generating current.
What is electromagnetic induction?
Short answer
Electromagnetic induction is the production of a voltage across a conductor when the magnetic field through it changes. Faraday’s law states that the induced EMF is proportional to the rate of change of magnetic flux; Lenz’s law says the induced current opposes that change. Induction is the principle behind electric generators and transformers.
Concept preview
What you will be able to do
- 01Define magnetic flux and state Faraday's law
- 02Use Lenz's law to find the direction of an induced current
- 03Explain how a changing magnetic field induces an EMF
We saw a current in a field feel a force (the motor). Electromagnetic induction is the stunning reverse: move a magnet near a coil and you generate a current — with no battery at all. Faraday and Henry discovered that a changing magnetic field through a loop drives a current. This one phenomenon powers every generator on Earth, every transformer, and the wireless charger on your desk. It is arguably the most important discovery in the history of technology.
School Plan
Induction
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Related topics
Frequently asked questions
- What does Lenz’s law state?
- The induced current flows in the direction that opposes the change in magnetic flux that produced it — a consequence of energy conservation.
- What is magnetic flux?
- A measure of the magnetic field passing through a given area; a change in flux is what induces a voltage.