 The work "W" required to move "q" from "A" to any point "B" in the electrostatic force field is given by
typically given in "J" for Joules.A related quantity called "electric potential" (commonly denoted with a "V" for voltage) is equal to the electric potential energy per unit charge.The energy of a magnetic moment formula_44 in an externally produced magnetic B-field has potential energy

The magnetization in a field is

where the integral can be over all space or, equivalently, where is nonzero.