Javascript® Electronic Notebook Kirchhoff's Law by Martin E. Meserve

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"The current flowing into a node or branching point is equal to the sum of the individual currents leaving the node or branch point."

A example of a branching circuit is shown in the calculator on the right. Each resistor is considered a node or branch. Nodes with higher resistance get less current and nodes with lower resistance get higher current. The sum of the individual node currents, I_{1} I_{2} I_{3}, is equal to the total current, I_{T}.

The calculator shows you the current relationships for 3 resistors (R1, R2, R3) in parallel, connected to a voltage source (E_{T}). You can change any of the input data values and see the resultant output in the output text area and on the drawing.

Note: If you wish to see the current relationships for only 2 resistors, leave one of the resistor values blank. Do Not use a "0" as this would draw Infinite current.

"The sum of the voltages in a closed current loop is zero."

This law is very similar to the first law, except that it deals with voltages instead of currents. An example would be the circuit to the right. In the case of a single voltage source, the sum of the individual voltage drops in the circuit is equal to the applied voltage. The current (I_{T}), in this case, is equal to the voltage (E) divided by the total resistance (R1+R2+R3).

The clculator shows you the voltage relationships for 3 resistors in series, connected to a voltage source. You can change any of the input data values and see the resultant output in the output text area and on the drawing.

Note: If you wish to see the current relationships for only 2 resistors, leave one of the resistor values blank, or set it to "0".