The diagram shows the phenomenon of electromagnetic induction.
Electromagnetic induction is a phenomenon in which a changing magnetic field across a loop of wire results in the generation of an induced emf. When there is relative motion between a magnet and the coil, magnetic flux changes and hence an electromotive force is generated in the coil.The phenomenon of electromagnetic induction is the existence of an induced current in a circuit (such as a coil) placed in a region where the magnetic field motion changes with the time. The magnetic field may change due to relative motion between coil and magnet placed near the coil
When a magnet is moved through a loop of wire, there is a change in magnetic field lines through the coil. This change in magnetic field again causes electromagnetic induction in the coil.On August 29 in 1831, British scientist Michael Faraday discovered electromagnetic induction, a seminal breakthrough which laid the groundwork for later researchers such as James Clerk Maxwell, and led to important inventions such as electric motors, transformers, inductors, and generators.
It occurs whenever a magnetic field and an electric conductor move relative to one another so the conductor crosses lines of force in the magnetic field. The current produced by electromagnetic induction is greater when the magnet or coil moves faster, the coil has more turns, or the magnet is stronger.Lenz's law is used for determining the direction of induced current. Lenz's law of electromagnetic induction states that the direction of induced current in a given magnetic field is such that it opposes the induced change by changing the magnetic field.