AC GENERATION
Basic AC Theory
The induced voltages add in series, making slip ring X (Figure 1) positive (+) and slip ring Y
(Figure 1) negative (-). The potential across resistor R will cause a current to flow from Y to
X through the resistor. This current will increase until it reaches a maximum value when the coil
is horizontal to the magnetic lines of force (Figure 2, 90o). The horizontal coil is moving
perpendicular to the field and is cutting the greatest number of magnetic lines of force. As the
coil continues to turn, the voltage and current induced decrease until they reach zero, where the
coil is again in the vertical position (Figure 2, 180o). In the other half revolution, an equal
voltage is produced except that the polarity is reversed (Figure 2, 270o, 360o). The current flow
through R is now from X to Y (Figure 1).
Figure 2 Developing a Sine-Wave Voltage
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