Inductors in Series

When two or more inductors are in series they can be replaced with a single, equivalent inductor with inductance given by: \(L_{eq} = L_1 + L_2 + ...\)

Simplify the circuit below:

This one is straightforward. We have two inductors in series (shocked aren't you?) so we add their inductances to get our equivalent inductance. \(L_{eq} = L_1 + L_2 = 12\)mH \( + 209\)mH \( = 221\)mH And we're done.
practice problems