Problem 55-20
Source: Question 2 of the 2nd Circuit Analysis II exam - PUC - 2014
Determine the voltage Vm in the circuit shown in Figure 55-20.1, knowing that
V = 40 ∠30° and I = 5 ∠0°.
Solution of the Problem 55-20
The best way to solve this problem is by the nodal method. However, before applying the method, let's do a little
source transformation with the current source and the 10 Ω resistor, as shown in Figure 55-20.2.
Note that since the two resistors, the one for 8 Ω and the one for 10 Ω, have assumed a series connection (due to transformation) and, thus, we add the two values resulting in a 18 Ω resistor. Now, applying the method nodal to the circuit, we get:
Joining the terms of Vm in the first member and passing the value of the sources to the second member, we have:
Carrying out the calculation on both sides, we get:
Carrying out the appropriate operations, we find
