This also follows from Ampère's law and is analogous to Kirchhoff's voltage law for adding resistances in series. Also, the sum of magnetic fluxes Φ Φ 1 , Φ Φ 2 , … … into any node is always zero: Φ Φ 1 + Φ Φ 2 + ⋯ ⋯ = 0.