Faraday's law of induction was discovered through experiments carried out y Micheal Faraday in England 1831 and by Joseph Henry in the united state at about the same time.
In the year 1831, a most important electrical discovery was made by Micheal Faraday. His life is a continuous record of brilliant research and experiment in chemistry and electricity.
Faraday found that if a magnet be ,moved toward or away from a coil of wire, or if the the wire be moved toward or away from a magnet, a momentary electric current is induced in the wire as shown in the figure. for example if the ends of the coil of insulated wire are attached to a galvanometer and if a bar magnet is moved in and of the coil, the galvanometer shows that a current is induced in the coil at two instants when the magnet is inserted when the it is withdrawn. We know that a magnet is surrounded by lines of magnetic force and Faraday found that the current was induced when these lines of forces were cut across.
Faraday also found that the two current produced in the experiments, flowed in opposite directions. the current that appeared in the experiment was called induced current and was said to be set up by an induced e.m.f.
whenever the numbers of lines of magnetic induction or magnetic flux through a conducting circuit changes, an induced e.m.f is produced in it. If the circuit is closed , a current floes. The emf or current lasts only for time the change in magnetic flux continues. The magnitude of the induced emf or current is proportional to the rate at which magnetic flux changes. The magnetic flux through a circuit can be changed by any of the following methods
1) by the motion of a magnet near the circuit or away from it or the motion of a circuit toward or away from magnet.
2) By rotation of a coil in a magnetic field.
3) By starting, stopping or changing the current in a neighboring circuit ( mutual induction )
4) By starting, stopping or changing the current in the circuit itself (Self-Induction).
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