Inductance

The self inductance L of coils or closed current wires describes the correlation between the current entering the device and the magnetic flux linkage caused by it:

Φ = L I    with

L = N2 P

L = self inductance

I = current

Φ = magnetic flux linkage

N = number of coil turns

P = magnetic permeance

The energy inside the magnetic field of a single current driven coil can be written as follows:

Wm =  ½ Φ I = ½ L I2 = ½ P N2 I2

Note: The formulas given above are valid only for linear materials or in other words: a constant permeance.