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AC Voltage Generation
We have already learned that when a conductor is made to cut through a magnetic field, a voltage is generated in the conductor. Notice the sheer presence of the conductor in a magnetic field is not enough, there must be movement of the conductor. Even movement in the direction of the magnetic field is not enough, the conductor must cut the lines of magnetic field.
The figure shown here illustrates what happens if a coil is moved to rotate in a magnetic field.
A magnetic field is present between north and south poles of a magnet (as shown in the figure). Notice the coil which is placed at the center of the magnetic field. This is a simple coil, consisting of only one turn.
If this coil is rotated, its loop will cut the magnetic lines of force. Therefore, voltage will be generated in the conductor that is used to make the coil. A question immediately comes to mind. In which direction will the current flow? Again, we have a simple answer to this question: Left Hand Rule for Generators.