Fig. 49. A STEADY DIRECT CURRENT
Fig. 50. AN INTERRUPTED DIRECT CURRENT
Fig. 51. A PULSATING DIRECT CURRENT
An alternating current, see Fig. 52, is one which flows first in one direction and then in the other direction. A magneto-electric machine and an alternating current generator are the means for generating this form of current. Alternating current can be produced from a direct current by using an induction coil, or spark coil as it is called. But a steady direct current can be obtained from an alternating current only by coupling an alternating current motor to a direct current dynamo.
Fig. 52. AN ALTERNATING CURRENT