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The Alternating Current

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-409

2025-12-14

630

The electromotive force generated in the ideal simple dynamo of Fig. 1 goes through a definite cycle of change, and when the current passes into an external circuit it also goes through a similar cycle. If time is laid off on the axis OX and current on the axis yy', the curved line of Fig. 2 will represent the changes that take place in an alternating current during the time of a single cycle.

In the first quarter of the time the current has increased from zero to a maximum in one direction. It then diminishes until at the end of one half the time the current is again zero. Reversal then takes place and the current rises to a maximum in the opposite direction in three fourths of the time and at the end of the cycle the current is again zero.

In the alternating current used for lighting there are 60 of these cycles per second.