Electrical Laws
Kirchhoff’s Current Law (KCL)
Kirchhoff’s current law states that the total current entering a node equals the total current leaving it, because charge cannot accumulate at an ideal node. Written algebraically, the sum of all currents at the node is zero once entering and leaving currents are given opposite signs. The law is used to write node equations for any network and remains valid for non-linear components.
Kirchhoff’s Current Law (KCL)
Σ I_in = Σ I_out
Variables and units
| Symbol | Quantity | Unit |
|---|---|---|
| I_in | Sum of currents entering the node | A |
| I_out | Sum of currents leaving the node | A |
Conditions of application
Charge conservation at a node of a lumped circuit; applies to linear and non-linear circuits. Use one consistent direction convention for entering and leaving currents.
Worked example
Solved
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