# FACTS Questions and Answers – Current-Sourced Versus Voltage-Sourced Converters – Set 2

This set of FACTS Multiple Choice Questions & Answers (MCQs) focuses on “Current-Sourced Versus Voltage-Sourced Converters – Set 2”.

1. The phenomenon of charging a capacitor by a constant current source is ________ charging a capacitor by a constant voltage source.
a) same to
b) different from
c) may be same to or different from
d) inverse to

Explanation: The phenomenon of charging a capacitor by constant current source and that by a constant voltage source are different. However, they do not bear any inverse relationship. Their respective characteristic graphs with respect to time reveal that they exhibit different behaviors.

2. An ideal current source shows ________ internal impedance.
a) infinite
b) zero
c) unknown
d) finite

Explanation: An ideal current source shows infinite internal impedance. An ideal current source provides constant current to the circuit irrespective of any circuit conditions. An ideal current source exhibits 100% efficiency.

3. An ideal voltage source shows ________ internal impedance.
a) infinite
b) zero
c) unknown
d) finite

Explanation: An ideal voltage source shows zero internal impedance. An ideal voltage source provides constant voltage to the circuit irrespective of any circuit conditions. An ideal voltage source exhibits 100% efficiency.

4. An ideal current source shows infinite output impedance in ________with the source.
a) parallel
b) series
c) series parallel combination
d) zig-zag connection

Explanation: An ideal current source shows infinite output impedance in parallel with the source. Therefore, the current flows away from the ideal current source towards the load connected in the circuit. This is because the current always choose the path of least resistance, and load resistance is less than the current source resistance.

5. An ideal voltage source shows zero output impedance in ________ with the source.
a) parallel
b) series
c) series parallel combination
d) zig-zag connection

Explanation: An ideal current source shows zero output impedance in series with the source. Therefore, the constant voltage from the ideal voltage source is available at the load connected in the circuit. This is because the voltage source resistance being zero, there is no voltage drop at the source.

6. Match the following.

Theorem Components
1] Thevenin’s theorem A] voltage source
B] resistance in parallel with the source
C] current source
D] resistance in series with the source

a) 1-A, 1-D
b) 1-A, 1-B
c) 1-C, 1-D
d) 1-A, 1-C

Explanation:

Theorem Measuring Units
1] Thevenin’s theorem A] voltage source
D] resistance in series with the source

7. The charging of capacitor by ________ maintains linearity with time.
a) a constant current source
b) a constant voltage source
c) either a constant current source or a constant voltage source
d) neither a constant current source nor a constant voltage source

Explanation: Basically the charging of capacitor by a constant current source maintains linearity with time. This is because the constant current source with constant current (say I) will impose a slope I/C (where C is the capacitance of the capacitor being charged) and voltage across the charging capacitor will vary linearly with time. The graph will be a straight line with slope I/C.

8. Match the following.

Theorem Components
1] Norton’s theorem A] voltage source
B] resistance in parallel with the source
C] current source
D] resistance in series with the source

a) 1-A, 1-D
b) 1-A, 1-B
c) 1-C, 1-B
d) 1-A, 1-C

Explanation:

Theorem Measuring Units
1] Norton’s theorem C] current source
B] resistance in parallel with the source

9. The charging of capacitor by ________ exhibits exponential relationship with time.
a) a constant current source
b) a constant voltage source
c) either a constant current source or a constant voltage source
d) neither a constant current source nor a constant voltage source

Explanation: Basically the charging of capacitor by a constant voltage source exhibits exponential relationship with time. A capacitor connected to a voltage source without a resistance will act like a short circuit. Therefore when a capacitor is charged through a resistance from a constant voltage source, it rises exponentially with time as the time constant RC comes into play (where R and C are the resistance and capacitance respectively).

10. On what type of source is Thevenin’s theorem based?
a) independent source
b) current dependent voltage source
c) voltage dependent current source
d) voltage dependent voltage source

Explanation: Thevenin’s theorem is based on an independent source. It utilizes the model of an independent voltage source with Thevenin resistance in series to it. Dependent source is not modeled in a Thevenin equivalent circuit.

11. On what type of source is Norton’s theorem based?
a) independent source
b) current dependent voltage source
c) voltage dependent current source
d) voltage dependent voltage source

Explanation: Norton’s theorem is based on an independent source. It utilizes the model of an independent current source with Norton resistance in parallel to it. Dependent source is never modeled in a Norton equivalent circuit.

12. Norton’s theorem is the ________ of Thevenin’s theorem.
a) dual
b) inverse
c) equal
d) converse

Explanation: Norton’s theorem is the dual of Thevenin’s theorem. This is because a Norton equivalent circuit can be converted to a Thevenin equivalent circuit and vice-e-verse. So Norton’s theorem is NOT the inverse, nor equal of Thevenin’s theorem.

13. Norton resistance is ________ Thevenin resistance for any circuit.
a) equal to
b) negative of
c) inverse of
d) reverse of

Explanation: Norton resistance is equal to Thevenin resistance for any circuit. This is because the equivalent resistance of the given circuit having current and/or voltage sources are found out using the same principle. The internal resistances of the sources are considered while evaluating the Norton or Thevenin resistance across the given terminals.

14. Norton equivalent circuit is ________ transformation of Thevenin equivalent circuit.
a) source
b) impedance
c) current
d) voltage

Explanation: Norton equivalent circuit is source transformation of Thevenin equivalent circuit. It is not impedance transformation, neither current nor even voltage transformation that can be applied to this duality. The voltage and current relation in the Norton equivalent circuit and Thevenin equivalent circuit are related to each other by Voltage(voltage source) = Current(current source)* Impedance(Thevenin/Norton).

15. Thevenin theorem can be applied, when the given circuit contains ________
a) only independent sources
b) only dependent sources
c) either independent or dependent sources
d) either independent or dependent sources or both

Explanation: Thevenin theorem can be applied, when the given circuit contains either independent or dependent sources or both. Thevenin theorem can also be applied to a circuit containing no sources. The later is done to find out only the equivalent Thevenin resistance.

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