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  1. Describe a rotating-coil generator and the use of slip rings.

generator can be described as an electric motor working in reverse – instead of using electrical energy to produce kinetic energy, kinetic energy is used to produce electrical energy.

In an alternating current (a.c.) generator, a rectangular coil is forced to spin in a magnetic field, as shown here. The coil is connected to brushes that press on two metal rings.
As the coil rotates, it cuts magnetic field lines, so an e.m.f. is generated, and a current flows. The slip rings in an a.c. generator provide an unbroken connection between the coil and circuit as it spins around, meaning that the current generated is always alternating. So every time the coil rotates 180°, the direction of the current alternates i.e. changes direction.

  1. Sketch a graph of voltage output against time for a simple a.c. generator.



Notes submitted by Lintha

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