Question

Consider the circuit shown in below figure.

The total inductance of the circuit is,
(a) 20 H
(b) 60 H
(c) 92 H
(d) 54 H
​

Answer 1

20H

Explanation:

For coil 1,   L1 – M12 + M13 = 16 - 10 + 4 = 10

For coil 2,  L2 – M21 – M23 = 20 - 10 - 8 = 2

For coil 3,  L3 + M31 – M32  = 12 + 4 - 8 = 8

LT = 10 + 2 + 8 = 20H

or                                    

LT = L1 + L2 + L3 –  2M12 – 2M23 + 2M12 = 20H