Chapter 6

Alternating Voltages and Currents

John Bird

6.1 The AC Generator

Let a single turn coil be free to rotate at constant angular velocity symmetrically between the poles of a magnet system as shown in Figure 6.1.

image

Figure 6.1 : Coil rotates at constant angular velocity

An e.m.f. is generated in the coil (from Faraday’s laws) which varies in magnitude and reverses its direction at regular intervals. The reason for this is shown in Figure 6.2. In positions (a), (e) and (i) the conductors of the loop are effectively moving along the magnetic field, no flux is cut and hence, no e.m.f is induced. In position (c) maximum flux is cut and maximum ...

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