Basic DC Theory KIRCHHOFF’S LAWSFor example, what is the current flow in Figure 34? Assume that the current is flowing in thedirection shown.Figure 34 Using Kirchhoff’s Voltage Law to find Currentwith Multiple Battery SourcesUsing Kirchhoff’s Voltage Law:E_{source}IR507030I10I2040II2040I0.5The result is negative. The current is actually 0.5 ampere in the opposite direction to that of theassumed direction.Kirchhoff’sCurrentLawKirchhoff’s second law is called his current law and states: "At any junction point in a circuit,the current arriving is equal to the current leaving." Thus, if 15 amperes of current arrives at ajunction that has two paths leading away from it, 15 amperes will divide among the twobranches, but a total of 15 amperes must leave the junction. We are already familiar withKirchhoff’s current law from parallel circuits, that is, the sum of the branch currents is equal tothe total current entering the branches, as well as the total current leaving the branches(Figure 35).Rev. 0 Page 45 ES-02

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