46. Find the voltage at node 1 of the circuit shown below.
A. 32.7
B. 33.7
C. 34.7
D. 35.7
Answer: B
Applying Kirchhoff’s current law at node 1,
10 = V1/10 + (V1 − V2)/3.
At node 2,
(V2 − V1)/3 + V2/5 + (V2 − 10)/1 = 0.
On solving the above equations, we get V1 = 33.7V.
47. Find the voltage at node 2 of the circuit shown below.
A. 13
B. 14
C. 15
D. 16
Answer: B
Applying Kirchhoff’s current law at node 1,
10 = V1/10 + (V1 − V2)/3.
At node 2, (V2 − V1)/3 + V2/5 + (V2 − 10)/1 = 0.
On solving the above equations, we get V2 = 14V.
48. In the superposition theorem, when we consider the effect of one voltage source, all the other voltage sources are ____________
A. Shorted
B. Opened
C. Removed
D. Undisturbed
Answer: A
In the superposition theorem when we consider the effect of one voltage source, all the other voltage sources are shorted and current sources are opened.
49. In the superposition theorem, when we consider the effect of one current source, all the other voltage sources are ____________
A. Shorted
B. Opened
C. Removed
D. Undisturbed
Answer: A
In superposition theorem, whether we consider the effect of a voltage or current source, voltage sources are always shorted and current sources are always opened.
50. In the superposition theorem, when we consider the effect of one voltage source, all the other current sources are ____________
A. Shorted
B. Opened
C. Removed
D. Undisturbed
Answer: B
In the superposition theorem when we consider the effect of one voltage source, all the other current sources are opened and voltage sources are shorted.
51. In the superposition theorem, when we consider the effect of one current source, all the other current sources are ____________
A. Shorted
B. Opened
C. Removed
D. Undisturbed
Answer: B
In superposition theorem, whether we consider the effect of a voltage or current source, current sources are always opened and voltage sources are always shorted.
52. Find the value of Vx due to the 16V source using Superposition Theorem.
A. 4.2V
B. 3.2V
C. 2.3V
D. 6.3V
Answer: B
When we consider the 16V source, we short the 10V source and open the 15A and 3A sources. From the resulting series circuit, we can use a voltage divider to find Vx.
Vx = 16 × 20/(20 + 80) = 3.2A.
53. Find Vx due to the 3A source using Superposition Theorem.
A. 56V
B. 78V
C. 38V
D. 48V
Answer: D
Due to the 3A source, we short the 16V and 10V sources and open the 15A source. From the resulting circuit, we can use a current divider to find the current in the 20-ohm branch and then multiply it with the resistance to find the voltage.
I20 = 3 × 80/(20 + 80) = 2.4A
Vx = 20 × 2.4 = 48V.
54. Find the value of Vx due to the 10V source using Superposition Theorem.
A. 1V
B. 2V
C. 3V
D. 4V
Answer: B
Due to the effect of the 10V source, we short the 16V source and open the 3A and 15A sources. From the resulting series circuit, we can use a voltage divider to find the value of Vx.
Vx = 10 × 20/(80 + 20) = 2V.
55. Find the voltage due to the 15A source.
A. 0V
B. 2V
C. 4V
D. 6V
Answer: A
Due to the 15 A current source, 10V, and 16V sources get shorted and the 3A source acts as an open circuit. Since the 10V source is shorted, it acts as a low resistance path, and current flows only within that loop and does not flow to the 20-ohm resistor. Hence the voltage is 0V.
56. Superposition theorem is valid for _________
A. Linear systems
B. Non-linear systems
C. Both linear and non-linear systems
D. Neither linear nor non-linear systems
Answer: A
The superposition theorem is valid only for linear systems because the effect of a single source cannot be individually calculated in a non-linear system.
57. Superposition theorem does not work for ________
A. Current
B. Voltage
C. Power
D. Works for all: current, voltage, and power
Answer: C
Power across an element is not equal to the power across it due to all the other sources in the system. The power in an element is the product of the total voltage and the total current in that element.
58. In the Superposition theorem, while considering a source, all other voltage sources are?
A. open circuited
B. short-circuited
C. change its position
D. removed from the circuit
Answer: B
In the Superposition theorem, while considering a source, all other voltage sources are short-circuited. This theorem is valid for linear systems.
59. In the Superposition theorem, while considering a source, all other current sources are?
A. short-circuited
B. change its position
C. open circuited
D. removed from the circuit
Answer: C
In the Superposition theorem, while considering a source, all other current sources are open-circuited. The superposition theorem is not valid for power responses. It is applicable only for computing voltage and current responses.
60. In the circuit shown, find the current through a 4Ω resistor using the Superposition theorem.
A. 4
B. 5
C. 6
D. 7
Answer: B
Considering the voltage source 20V, 5A current source is open-circuited.
Now current through 3Ω resistor is
20/(5 + 4) = 2.22A.
Now considering the current source 5A, the 20V voltage source is short-circuited.
No current through a 3Ω resistor is
5 × 5/(4 + 5) = 2.78A.
Now finally the current through 3Ω resistor is 2.22 + 2.78 = 5A.
