Electromagnetism created a revolution by leading to the devices called motors which convert electrical energy to mechanical energy. Experiments by scientists like Oersted and Faraday made a long leap by converting mechanical energy to electrical energy. When a straight conductor is moved in a magnetic field an electric current is induced in it and the phenomenon is electromagnetic induction. The emf caused is the induced emf and the current is induced current. Oersted found the same by relative motion of a magnet with respect to a coil. Faraday's experiment proved that the strength of the induced current depends on several factors like the strength of the magnet, the speed of motion of the magnet, its orientation, the number of turns in the coil and the diameter of the coil. The induced current can be detected by a galvanometer.
Electric generators work on the same principle. They have an armature which is free to rotate in a magnetic field. Its terminals are connected to two slip rings, which are further connected to two brushes and they are connected across a load resistance through which the generated electricity can be trapped. The rotation of the armature in the magnetic field changes the magnetic flux in the coil of the armature and an electric current is induced. For every half rotation, the direction of the induced changes and hence called alternating current.
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