Polarity and direction of current flow
Earlier you learned about the term polarity, referring to the charge at one point with respect to another. When working with electrical circuits, we often refer to the polarity between different points in the circuit. Understanding polarity is important for connecting the leads of polarity-dependent devices such as some meters and motors. Polarity is also important for determining the direction of current flow. In Figure 10 the current leaves the source at the negative terminal, travels around the circuit in a clockwise direction, and re-enters the source at the positive terminal.
It is important to notice that current flows through loads from negative to positive, and current flows through sources from positive to negative. A more precise way of stating this is that outside the source, current flows from negative to positive, but inside the source current flows from positive to negative.
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