, where:

F = Force (N)

= Gradient

m = Magnetic Moment (A*m^{2})

= Dot Product

B = Magnetic B-Field (T)

,

, where:

I = Current (A)

J = Current Density (A/m^{2})

And the subscripts:

(none) = Total

F = Free

M = Magnetization

P = Polarization

, or

, where:

= Divergence

B = Magnetic B-Field (T)

S = Closed 3-D Surface

Hopkinson's Law for magnetic circuits defines the magnetic reluctance as:

, where:

R = Magnetic Reluctance (A/Wb)

F = Magnetomotive Force (A)

= Electric Flux (Wb)

The magnetic constant in physics, also known as vacuum permeability or permeability of free space, it uses the symbol mu nought (u0) for the value:

, where:

= Magnetic Constant (Magnetic Field Constant), also known as Vacuum Permeability (H/m)

Note that mu naught over four pi also provides a relevant result: