Análise de Circuitos de Corrente Alternada - Prova 1

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AC Circuit Analysis
First Midterm
Prof. Diego Mejía-Giraldo
October 9, 2020
Name: ID:
Open notes, open book, calculator is allowed, 110-minute time limit. Good luck!!.
Problem 1. (12 points.) The expressions for the steady-state voltage and current at the terminals
of a circuit are
v = 8 sin (2 t + 150◦)
i = 16 cos (2 t + 100◦)
What are the parameters (R and L or C) of the equivalent element in parallel that can be
represented at the terminals of the circuit?
Problem 2. (20 Points.) Find the values of the elements (in Ω, H, or F) in the circuit of Fig. 1 that
guarantee that both circuits illustrated below will have the same admittance between terminals
a, b at 1 rad/s.
b
?
1/2 S
a
b
? j/4 S
a
Figure 1: Circuit of problem 2
Problem 3. (24 points.) Consider the circuit in Fig. 2. Obtain the short-circuit current flowing
from terminal a to terminal b.
1
2Vx
+
−1 0◦
1 Ω j1Ω
+
−
Vx 1Ω
b
a
1 90◦ A −j
Figure 2: Circuit of problem 3
Problem 4. (24 points.) For the circuit shown in Fig. 2, obtain the Thevenin/Norton impedance
seen between terminals a and b. You can choose your favorite approach to do this.
Problem 5. (24 points.) In the network of Fig. 3, the reactive element is unknown. Measurements
indicate that |Ig| = 1/2 |I| when ω = 1/12 rad/s and Ib lags I. Consider g = 2
√
3 S. Determine the
type and value of the reactive element (L or C).
I g
Ig
jb
Ib
Figure 3: Circuit of Problem 5
2