If two coils are direct-coupled as shown in the figure Bellow, the mutual inductance depends on coupling coefficient (k) and the next formulas can be used.
Formula 1
Where:
M is the mutual inductance in henry (H)
K is the coupling coefficient (between 0 and 1) as shown in the figure.
L1, L2 are the inductance of the coupled coils in henry (H)
The coupling coefficient is related to the amount of magnetic field lines produced by one coil that cuts the other coil in an angle that causes induction of an emf.
Derivated Formulas:
Formula 2
