Two coils having self-inductance of 10 H and 15 H are connected in series aiding connection. Find total inductance of the series connection, if the mutual inductance between the coils is 2.5 H.

Concept:

Series Aiding:

The equivalent inductance of series aiding connection is:

Leq = L1 + L2 + 2M

Series Opposing:

The equivalent inductance of series opposing connection is:

Leq = L1 + L2 – 2M

Calculation:

Given,

L₁ = 10 H

L₂ = 15 H

M = 2.5 H

The equivalent inductance for series addition is,

Leq = 10  + 15  + 2 x 2.5  = 30 H

Important Points

The equivalent inductance of the parallel aiding connection is:

Leq = \(\frac{{{L_1}{L_2} - {M^2}}}{{{L_1} + {L_2} - 2M}}\)

The equivalent inductance of the parallel opposing connection is

Leq = \(\frac{{{L_1}{L_2} - {M^2}}}{{{L_1} + {L_2} + 2M}}\)