20.5.5—Faraday’s and Lenz’s laws of electromagnetic induction

Faraday’s law states that induced emf magnitude is the rate of change of flux linkage; Lenz’s law says the induced effect opposes the change causing it.

Change field, area, orientation, turns or motion to change linkage, and use the negative sign as a direction rule.

Moving a magnet faster into a coil produces a larger transient emf; withdrawing it reverses the induced current.

The negative sign does not mean emf is negative in every measurement; it encodes opposition to the change.