Hopkinson's law (MMF)


where R is the electrical resistance of that material. Hopkinson’s law is a counterpart to Ohm’s law used in magnetic circuits. In electronic circuits, Ohm’s law is an empirical relation between the EMF applied across an element and the current I it generates through that element. Hopkinson’s law can be interpreted either as an empirical equation that works for some materials, or it may serve as a definition of reluctance.

Related formulas


MMFThe Magnetomotive Force (A*turns)
ΦThe Magnetic Flux through the magnetic element (Wb)
RmThe Magnetic Reluctance of the element (A*turns/Wb)