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Kirchhoff's Laws

Author: E.E. Kimberly

Kirchhoff has propounded two laws relating to electrical circuits, and they now bear his name. In his first law, Kirchhoff stated that there is always as much current flowing away from a point in a circuit as there is flowing to that point. For example, in Fig. 3-7 at the point M, the sum of the currents Ib and Im flowing away from M is equal to the current Ia flowing to M. This law is sometimes called Kirchhoff's law of currents.

Fig. 3-7. Three-Wire Distribution

In his second law, Kirchhoff stated that the sum of all voltage drops around any one path of an electric circuit equals the sum of the voltages impressed on that same path. For example, in Fig. 3-7, the equations are:

This law is


sometimes called Kirchhoff's law of voltages.

Last Update: 2010-10-05