Definition
Electromagnetic Induction is the production of an electromotive force (voltage) across an electrical conductor in a changing magnetic field.
Why It Matters
It is the physical basis for power generators, transformers, and induction motors.
Core Concepts
- Magnetic Fields: Produced by electron spin and revolution. Field lines spread from North to South.
- Magnetic Domains: Clusters of aligned atoms. In permanent magnets, domains are aligned.
- Electromagnets: Coils of wire that become magnets when current flows through them.
- Magnetic Force on Moving Charges: A magnetic field exerts a force perpendicular to the charge’s velocity. This is how we steer electrons in old TVs or particles in accelerators.
- Faraday’s Law: Induced Voltage Number of Loops Rate of Magnetic Field Change.
- How to read: “The induced voltage is proportional to the number of loops times the rate of change of the magnetic field.”
- Meaning / when to use: More coil turns and faster flux change produce larger induced EMF. This is the operating principle of generators and transformers.
- Lenz’s Law: The induced current creates a magnetic field that opposes the change that created it (Conservation of Energy).