The Standard Electrical Dictionary

1. Kirchoff's Laws

   These relate to divided circuits. I. When a steady current branches, the quantity of electricity arriving by the single wire is equal to the quantity leaving the junction by the branches. The algebraical sum of the intensities of the currents passing towards (or passing from) the junction is equal to zero; Summation(C) = 0 (Daniell.) In the last sentence currents flowing towards the point are considered of one sign and those flowing away from it of the other. II. In a metallic circuit comprising within it a source of permanent difference of potential, E, the products of the intensity of the current within each part of the circuit into the corresponding resistance are, if the elements of current be all taken in cyclical order together, equal to E; Summation(C * r) =E. In a metallic circuit in which there is no source of permanent difference of potential E = 0, and Summation(C * r)  = 0. This law applies to each several mesh of a wire network as well as to a single metallic loop, and it holds good even when an extraneous current is passed through the loop. (Daniell.) In this statement of the two laws E stands for electro-motive force, C for current intensity; and r for resistance of a single member of the circuit. [Transcriber's note: These laws may be restated as: At any point in an steady-state electrical circuit, the directed sum of currents flowing towards that point is zero. The directed sum of the electrical potential differences around any closed circuit is zero.]