Problem 13-12    Source:   Problem created by the site's author.

For the circuit shown in Figure 13-12.1, using Kirchhoff's law, determine:

a) The value of the current I.

b) The voltage V_x.

Solution of the Problem 13-12   -    Kirchhoff's Method

Item a

Looking at the circuit shown in Figure 13-12.1, we immediately recognize that:

On the other hand, doing the mesh equation as indicated by the green arrow, starting with the voltage source of 20 V, we obtain:

Rearranging algebraically, we find:

Then, substituting the equation eq. 13-12.1 into eq. 13-12.2, we obtain :

Carrying out the calculation, we find:

The negative value of I indicates that the direction of the current in the circuit is opposite to that indicated by the green arrow in Figure 13-12.1.

Item b

To calculate the value of V_x, simply use the equation eq. 13-12.1 and the value of I. Soon: