Lenz's Law

Lenz's law gives the direction of induced current. It states: > The induced current flows in a direction such that the magnetic effect it produces opposes the change that caused it. The induced effect opposes the change in magnetic flux, not necessarily the magnetic field itself.

If a north pole approaches a coil, the coil produces a magnetic field that opposes the approach. The near side of the coil behaves like a north pole.

If the same pole moves away, the coil produces a magnetic effect that tries to oppose the decrease in flux.

Lenz's law is consistent with conservation of energy. If induced current helped the change instead of opposing it, energy could be produced without corresponding work.