Hopkinson's law - Aetherwisp

Hopkinson's law is a magnetic analog of Ohm's law in the context of magnetic circuits. It connects the magnetic flux $\Phi_{B}$ of the circuit with its magnetic potential $V_{M}$ through the magnetic reluctance $\mathcal{R}$ :

V_{M}=\mathcal{R}\Phi_{B}

Like in Ohm's law, the potential is more correctly the magnetomotive force of the circuit.