Question

In a simple electric generator, a conducting loop of wire is placed in a magnetic field. The loop of wire is then rotated. Why is it necessary for the wire to be rotated?

Answer 1

Explanation:

If a coil of wire is placed in a magnetic field and rotated, an alternating (sinusoidal) current is induced. As it rotates, sometimes it is cutting through lots of magnetic flux, and so lots of current is

induced.

At other times, it is moving parallel to

the flux, and so no flux is cut, and no current is induced. In between, some current is induced. This creates an alternating current. Either end of the coil can be connected to wires outside of the generator in order to use the current elsewhere. This would be fine for the

first few rotations, but after this, the wires would get tangled up and the generator would be useless. To avoid this, we use a commutator. In an AC generator, this is a pair of rotating conducting 'slip rings' attached to either end of the coil. Carbon brushes bring these into contact with the outside world.