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Faraday's laws; Fleming's rules

Short answer

Faraday's first law: changing flux linkage induces emf. Second law: emf magnitude is -N dΦ/dt. Lenz's law gives direction opposing flux change.

Explain Faraday's laws of electromagnetic induction.

Faraday's laws describe how an emf is induced in a circuit when the magnetic flux linked with it changes.

First law

Whenever the magnetic flux linked with a circuit changes, an emf is induced in it. The emf lasts only as long as the flux is changing. (Flux can change by moving the conductor or magnet, or by varying the current producing the flux.)

Second law

The magnitude of the induced emf is equal to the rate of change of flux linkage.

e = − N dφ/dt     (volts)
  • N = number of turns, φ = flux in webers.
  • The negative sign is Lenz's law: the induced emf drives a current whose magnetic effect opposes the change producing it. This is a consequence of conservation of energy.

Example: a coil of 100 turns in which the flux changes from 0 to 5 mWb in 0.1 s has an average emf of 100 × 0.005/0.1 = 5 V.

✓ Answer checked by Claude Opus 5.5 (high effort)

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