Problem 54-4    Fonte:   Problem 1 - RLC Problem List - Discipline Engineering School Electrical Circuits - UFRGS - 2011 - Prof. Dr. Valner Brusamarello.

Determine the impedance Z in the circuit shown in Figure 54-4.1, so that we have I₂ = 10 ∠0°.

Solution of the Problem 54-4   

First, the current source is disregarded, as it is in parallel with the voltage source. Determining the Thévenin equivalent for the points b-c.

And the impedance of Thévenin will be the parallel between the two inductors, or:

Then, in the Figure 54-4.2, the new circuit configuration is shown after calculating the equivalent Thévenin.

From the statement of the problem, we know that I₂ = 10∠0°. So, this allows you to calculate Z_in, which is the total impedance that the circuit offers to the voltage source.

Now, as all the components that are part of the circuit are in series, adding all of them must be obtained Z_in. So:

Performing the calculation:

That is, the impedance Z must be composed of a resistor of 5 ohms in series with an inductor that has a reactance of 0.8 ohms , so that the value of I₂ is requested in the problem statement.