Question 1

- find the Thevenin impedance Zth).

Accepted Answer

A)  74.1 246.9° Ω 
B)  54.3 247.2° Ω 
C)  60 253.1° Ω 
D)  44.7 263.4° Ω 
A)  74.1 246.9° Ω 
B)  54.3 247.2° Ω 
C)  60 253.1° Ω 
D)  44.7 263.4° Ω C

Question 2

For the circuit with output impedance of 100 Ω- j20 Ω, how much power is delivered to a matched load if the voltage VS = 25 V rms?

Accepted Answer

A)  1.56 W 
B)  6.25 W 
C)  3.12 W 
D)  12.5 W 
A)  1.56 W 
B)  6.25 W 
C)  3.12 W 
D)  12.5 W A

Question 3

If the output impedance of a certain circuit is 100 Ω - j20 Ω, what value of load impedance will result in maximum power transfer to the load?

Accepted Answer

A)  20 Ω - j100 Ω 
B)  100 Ω + j20 Ω 
C)  20 Ω+ j100 Ω 
D)  100 Ω- j20 Ω 
A)  20 Ω - j100 Ω 
B)  100 Ω + j20 Ω 
C)  20 Ω+ j100 Ω 
D)  100 Ω- j20 Ω B

Question 4

Thevenin's equivalent circuit is the transformation of Norton's equivalent circuit.

Accepted Answer

A) True 
 B)False

Question 5

The Norton's equivalent circuit is characterized by the:

Accepted Answer

A)  equivalent voltage source in parallel with an equivalent impedance 
B)  equivalent voltage source in series with an equivalent impedance 
C)  equivalent current source in parallel with an equivalent impedance 
D)  equivalent current source in series with an equivalent impedance 
A)  equivalent voltage source in parallel with an equivalent impedance 
B)  equivalent voltage source in series with an equivalent impedance 
C)  equivalent current source in parallel with an equivalent impedance 
D)  equivalent current source in series with an equivalent impedance

Question 6

If two equal currents are in opposing directions at any instant in time, in a given branch, what is the net current at that instant?

Accepted Answer

A)  1 A 
B)  zero 
C)  the complex conjugate of the two 
D)  their sum 
A)  1 A 
B)  zero 
C)  the complex conjugate of the two 
D)  their sum

Question 7

Maximum power is transferred to a load when the load impedance is a complex conjugate of the output impedance of the driving circuit.

Accepted Answer

A) True 
 B)False

Question 8

The Norton current is found by calculating the between the marked terminals.

Accepted Answer

A)  source current 
B)  open circuit voltage 
C)  short circuit current 
D)  load current 
A)  source current 
B)  open circuit voltage 
C)  short circuit current 
D)  load current

Question 9

Norton's theorem provides a method for the reduction of any ac circuit to an equivalent form consisting of an equivalent current source in parallel with an equivalent impedance.

Accepted Answer

A) True 
 B)False

Question 10

Thevenin's theorem provides a method for the reduction of any ac circuit to an equivalent voltage source in parallel with an equivalent impedance.

Accepted Answer

A) True 
 B)False

Question 11

Why is the superposition theorem useful in the analysis of multiple-source circuits?

Accepted Answer

A)  because all sources are openend 
B)  because all sources are shorted out 
C)  the circuit can be analyzed one source at a time 
D)  because only Ohm's law is required 
A)  because all sources are openend 
B)  because all sources are shorted out 
C)  the circuit can be analyzed one source at a time 
D)  because only Ohm's law is required

Question 12

-Given Figure 19-3, find the Thevenin voltage Vth) for the circuit external to RL.

Accepted Answer

A)  15 253.1° V 
B)  8.3 263.4° V 
C)  11.2 263.4° V 
D)  13.2 253.1° V 
A)  15 253.1° V 
B)  8.3 263.4° V 
C)  11.2 263.4° V 
D)  13.2 253.1° V

Question 13

Figure 19-5
-See Figure 19-5. Using the superposition theorem, what is the portion of the current through the capacitor caused by the 5 V 230° voltage source?

Accepted Answer

A)  0.822 A 29.5° 
B)  0.616 A 2129.5° 
C)  0.741 A 255.6° 
D)  0.89 A 293.4° 
A)  0.822 A 29.5° 
B)  0.616 A 2129.5° 
C)  0.741 A 255.6° 
D)  0.89 A 293.4°

Question 14

-Given the circuit in Figure , what load value should be used to replace R2 to obtain the maximum power transfer to the load? Determine the type of load, and express the value in rectangular form.

Accepted Answer

A)  168 Ω - j76.8 Ω 
B)  88.1 Ω - j39.4 Ω 
C)  168 Ω + j76.8 Ω 
D)  64.1 Ω- j73.6 Ω 
A)  168 Ω - j76.8 Ω 
B)  88.1 Ω - j39.4 Ω 
C)  168 Ω + j76.8 Ω 
D)  64.1 Ω- j73.6 Ω

Question 15

The superposition theorem is useful for the analysis only in ac circuits.

Accepted Answer

A) True 
 B)False

Question 16

Maximum power transfer occurs when the ac impedances are:

Accepted Answer

A)  smaller 
B)  equal 
C)  larger 
D)  complex conjugates 
A)  smaller 
B)  equal 
C)  larger 
D)  complex conjugates

Question 17

What is the complex conjugate of 75 Ω + j45 Ω?

Accepted Answer

A)  75 Ω - j45 Ω 
B)  -75 Ω + j45 Ω 
C)  -75 Ω - j45 Ω 
D)  45 Ω - j75 Ω 
A)  75 Ω - j45 Ω 
B)  -75 Ω + j45 Ω 
C)  -75 Ω - j45 Ω 
D)  45 Ω - j75 Ω

Question 18

An equivalent voltage source in series with an equivalent impedance means you should solve the problem using:

Accepted Answer

A)  Thevenin's theorem 
B)  Norton's theorem 
C)  the superposition theorem 
D)  Millman's theorem 
A)  Thevenin's theorem 
B)  Norton's theorem 
C)  the superposition theorem 
D)  Millman's theorem

Question 19

The superposition theorem is useful for the analysis of multiple source circuits.

Accepted Answer

A) True 
 B)False

Question 20

Figure 19-1
-Given the circuit in Figure 19-1, find the total circuit current.

Accepted Answer

A)  12 mA 
B)  9 mA 
C)  18.2 mA 
D)  6 mA 
A)  12 mA 
B)  9 mA 
C)  18.2 mA 
D)  6 mA

Exam 19: Circuit Theorems in Ac Analysis

- find the Thevenin impedance Zth).

For the circuit with output impedance of 100 Ω- j20 Ω, how much power is delivered to a matched load if the voltage VS = 25 V rms?

If the output impedance of a certain circuit is 100 Ω - j20 Ω, what value of load impedance will result in maximum power transfer to the load?

Thevenin's equivalent circuit is the transformation of Norton's equivalent circuit.

The Norton's equivalent circuit is characterized by the:

If two equal currents are in opposing directions at any instant in time, in a given branch, what is the net current at that instant?

Maximum power is transferred to a load when the load impedance is a complex conjugate of the output impedance of the driving circuit.

The Norton current is found by calculating the between the marked terminals.

Norton's theorem provides a method for the reduction of any ac circuit to an equivalent form consisting of an equivalent current source in parallel with an equivalent impedance.

Thevenin's theorem provides a method for the reduction of any ac circuit to an equivalent voltage source in parallel with an equivalent impedance.

Why is the superposition theorem useful in the analysis of multiple-source circuits?

-Given Figure 19-3, find the Thevenin voltage Vth) for the circuit external to RL.

Figure 19-5 -See Figure 19-5. Using the superposition theorem, what is the portion of the current through the capacitor caused by the 5 V 230° voltage source?

-Given the circuit in Figure , what load value should be used to replace R2 to obtain the maximum power transfer to the load? Determine the type of load, and express the value in rectangular form.

The superposition theorem is useful for the analysis only in ac circuits.

Maximum power transfer occurs when the ac impedances are:

What is the complex conjugate of 75 Ω + j45 Ω?

An equivalent voltage source in series with an equivalent impedance means you should solve the problem using:

The superposition theorem is useful for the analysis of multiple source circuits.

Figure 19-1 -Given the circuit in Figure 19-1, find the total circuit current.

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