Problem 4-4    Source:   Problem elaborated by the author of the site.

Suppose the circuit is in permanent regime. Calculate the energy stored by the inductors in the circuit show in Figure 04-04.1.

Solution of the Problem 4-4

As the problem says that the system is in permanent regime, then we already know that the inductors behave as short circuit. This allows you to calculate the current passing through each inductor taking into account only the values resistor of the circuit. And, of course, they are in parallel. Then, first, let's compute the current through the inductor of 2 H that is in series with the resistor of 10 ohms. To do this, we will use a current divider. So:

Now let's calculate the current passing through the inductor of 5 H that is in series with the resistor of 20 ohms, or:

With the values of the electric currents that circulate through the inductors we can calculate the energy accumulated in each of them using the eq. 04-05 reproduced below.

Then we have the following values: