Page 272 - Basic Electrical Engineering
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Figure 3.1 Concept of dc and ac illustrated. (a) A battery connected to a resistive load; (b) direct
current of constant magnitude; (c) direct current of variable magnitude; (d) a battery connected to a
resistive load through a reversing switch; (e) alternating current of square–wave shape; (f) alternating
current of rectangular wave shape
When the direction of current through a circuit continuously changes, such
a current is called alternating current. The polarities of the ac supply source
changes alternately and causes alternating current to flow through the load
connected across the terminals. Fig. 3.1 (a) shows dc flowing through the
