Electromagnetic Induction
Electromagnetic induction is the production of emf in a conductor when the magnetic flux linked with it changes, described qualitatively by Faraday’s and Lenz’s laws.
Try the simulator
Changing flux
An emf is induced in a coil when the magnetic flux linked with it changes. This can happen by moving a magnet towards or away from the coil, moving the coil in a magnetic field, or changing the current in a nearby coil. Faster change in flux produces larger induced emf.
Direction of induced current
Lenz’s law states that the direction of induced current is such that it opposes the change in flux that produced it. This explains why pushing a magnet into a coil feels harder when current is induced, and why the induced current direction reverses when you reverse the motion.
Why does a galvanometer needle deflect in opposite directions when a magnet is moved into and out of a coil?