This document discusses how alternating current (AC) voltage is generated. As a coil rotates at a constant speed between the poles of a magnet, an electromotive force (emf) is induced in the coil according to Faraday's Laws. The emf varies in magnitude and reverses direction regularly. Maximum emf is induced when the coil is in positions where maximum magnetic flux is cut. As the coil rotates through one revolution, one cycle of alternating emf is produced, following the principle of operation of an AC generator or alternator.

1. Generation
of AC Voltage

2. 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.

3. 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 output
waveform is shown in Figure.

4. In positions (a),(c) and (e) the
conductors moving along the magnetic
field, no flux is cut and hence no e.m.f. is
induced.

5. In position (b) maximum flux is cut and
hence maximum e.m.f. is induced. In
position (d), maximum flux is cut and
hence maximum e.m.f. is again induced.

6. However, using Fleming’s right-hand rule, the
induced e.m.f. is in the opposite direction to
that in position (c) and is thus shown as -V. If
all such positions of the coil are considered,
in one revolution of the coil, one cycle of
alternating e.m.f. is produced as shown. This
is the principle of operation of the ac
generator (i.e. the alternator).

7. If you like video then click on
subscribe button to get notification of
latest uploaded video.