Kirchhoff’s Current Law
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FIGURE 36-34
Kirchhoff’s current law: Current entering a junction is equal to the sum of the current flowing out of the junction.

Kirchhoff’s current law describes a fundamental electrical principle and is used by technicians in understanding how all electrical circuits work. Many technicians would understand the principle behind the law without necessarily associating it with Kirchhoff. Simply stated, the law is that current entering any junction is equal to the sum of the current flowing out of the junction. For example, in a junction of three conductors, current is flowing in at 10 amps from conductor A and out by the other two conductors, B and C Figure 36-34. According to Kirchhoff’s current law, the sum of the current in conductors B and C will equal the current flowing into the junction at conductor A, or 10 amps.