Electric Circuits Questions and Answers – Source Transformations

This set of Electric Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Source Transformations”.

1. By using source transformation voltage source in series resistor is replaced by __________
a) Voltage source in series with a resistor
b) Current source in parallel with a resistor
c) Voltage source in parallel with a resistor
d) Current source in series with a resistor
View Answer

Answer: b
Explanation: In Source transformation, a voltage source in series with a resistor is replaced by a current source in parallel with the same resistor and vice versa.

2. Source Transformation is _____________
a) Unilateral
b) Unique
c) Bilateral
d) Complicated
View Answer

Answer: c
Explanation: In Source transformation, a voltage source in series with a resistor is replaced by a current source in parallel with the same resistor and vice versa. So, it is bilateral.

3. If there are two resistors in parallel and in series with a voltage source then ___________
a) Parallel resistor has no effect
b) Series resistor has no effect
c) Both has their respective effects
d) Both has no effect on the voltage source
View Answer

Answer: a
Explanation: In source transformation, the voltage source in series with a resistor to be replaced by a current source in parallel with the same resistor and vice versa. So other resistors are redundant and have no effect.
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4. Using source transformation, calculate the voltage.
The voltage is 39V using source transformation
a) 4.33V
b) 39V
c) 0.230V
d) 36V
View Answer

Answer: b
Explanation: V=IR=13*3=39V.

5. Which element(s) has no effect in the given circuit?
10Ω element is redundant & has no effect in the given circuit
a) 7Ω
b) 10Ω
c) Both 7Ω and 10Ω
d) Voltage source.
View Answer

Answer: b
Explanation: Voltage in series with a resistor in replaced by a current source but here 10Ω is in parallel. So, it is redundant and has no effect.
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6. The value of current source is __________ after replacing the given network with a single current source and a resistor.
Value of current source is 80V after replacing network with single current source
a) 70V
b) 60V
c) 90V
d) 80V
View Answer

Answer: d
Explanation: In the given circuit 9Ω resistor has no effect.
10*6=60V, 60V+20V=80V.

7. If there is a 12A current source in series with 2Ω and in parallel with a 4Ω resistor, then voltage V=?
a) 24V
b) 48V
c) 3V
d) 6V
View Answer

Answer: b
Explanation: 2Ω resistor is redundant. 12*4=48V.
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8. Find the current flowing through 4Ω resistor shown in network below.
Find the current flowing through 4Ω resistor shown in network
a) 1.33A
b) 2.35A
c) 1.66A
d) 2.66A
View Answer

Answer: c
Explanation: By using source transformation the above network is reduced and then by current division rule I4Ω= 5*(2/2+4) =1.66A.

9. Calculate the power delivered by the 50V source.
The power delivered by 50V source is 274W by using source transformation
a) 274W
b) 276W
c) 285W
d) 291W
View Answer

Answer: a
Explanation: By using source transformation the above network is reduced and current in the circuit is found out and later power delivered by 50V source= 50*current in the circuit= 50*5.48A= 274W.
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10. Source transformation can be used for dependent sources.
a) True
b) False
View Answer

Answer: a
Explanation: Source transformation can be used for dependent sources. However, the controlling variable must not be tampered with any way since the controlled source operation depends on it.

11. Using source transformation, calculate vm.
The vm is -2v using source transformation
a) 2v
b) -2v
c) 1v
d) -1v
View Answer

Answer: b
Explanation: Using source transformation, the network is reduced and at last voltage is obtained.

12. Find the voltage value Vm in the circuit given below.
The voltage value Vm in the circuit given is -3V using source transformation
a) -3V
b) 3V
c) 2.1V
d) -2.1V
View Answer

Answer: a
Explanation: Using source transformation, the voltage source in series with a resistor to be replaced by a current source in parallel with the same resistor and vice versa.

13. Source transformation technique is mainly based on __________ law.
a) Newton’s
b) Kirchhoff’s
c) Ohm’s
d) Einstein’s
View Answer

Answer: c
Explanation: Ohm’s law: V=iR. By using this, the voltage/ current sources are reduced.

14. In source transformation,
a) Voltage sources remain same
b) Current sources remain same
c) Both voltage and current sources undergo change
d) Resistances/Impedances remain same
View Answer

Answer: d
Explanation: In source transformation, only the particular voltage/current sources change whereas the resistances remain same.

15. If there are five 20V voltage sources in parallel, then in source transformation __________
a) All are considered
b) Only one is considered
c) All are ignored
d) Only 2 are considered
View Answer

Answer: b
Explanation: In parallel, voltages are same. So, only is considered and rest are ignored.

Sanfoundry Global Education & Learning Series – Electric Circuits.

To practice all areas of Electric Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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