Kirchhoff's Circuit Laws
Two fundamental circuit laws expressing current conservation at nodes and the algebraic sum of voltage changes around a closed loop.
Kirchhoff's laws bring two conservation ideas into circuit analysis.
Kirchhoff's Current Law (KCL) states that the algebraic sum of signed currents at a node is zero:
Σ I = 0Kirchhoff's Voltage Law (KVL) states that the algebraic sum of signed voltage changes around a closed loop is zero:
Σ V = 0KCL underpins nodal analysis; KVL underpins mesh and loop analysis. The reference directions are conventional rather than unique, but the sign convention must remain consistent within the equations.
These laws are extremely effective in lumped circuits. At scales where distributed electromagnetic effects matter, the circuit model itself may need to be extended.
Worked context: Circuit Theory.