Problem 17-2    Source:   Problem created by the site's authors.

For the circuit shown in Figure 17-02.1, determine the values ​​of I and I₁ using the Linearity theorem.

Solution of the Problem 17-2

To use the Linearity theorem we must provide a numerical value for the current I₁. Let us then make I₁ = 4 A. This way, we can calculate the value of V_ab, or:

With the value of V_ab it is possible to calculate the value of the current I₂, that is:

Therefore, we can calculate the value of I, as we know that:

And now we can calculate the value of the voltage source that generates I = 5 A.

At this point the question to ask is: if a voltage source of 200 V generates a current I₁ = 4 A, what will be the current value I₁ when the voltage source has its value changed to 60 V ? Just use a simple rule of three, or:

Knowing the value of the current I₁, we can calculate I₂, knowing that V _ab = 20 x 1.2 = 24 V. Soon:

Then, the value of I will be: