ISCET DC Circuit Analysis 5 — Questions and Answers
Question 1: What is the conductance of a 25Ω resistor?
- 0.04 S (Correct answer)
- 25 S
- 0.4 S
- 4 S
Correct answer: 0.04 S
Conductance G = 1/R = 1/25 = 0.04 siemens (S).
Question 2: A circuit has nodes A, B, and C. Using node voltage analysis, how many independent node equations are needed if C is the reference node?
- 2 (Correct answer)
- 3
- 1
- 4
Correct answer: 2
With 3 nodes and 1 reference, you need 3 − 1 = 2 independent node voltage equations.
Question 3: Two 6V batteries are connected series-opposing in a loop with a 3Ω resistor. What current flows?
- 0A (Correct answer)
- 4A
- 2A
- 12A
Correct answer: 0A
Series-opposing batteries cancel each other: net EMF = 6 − 6 = 0V, so current = 0A.
Question 4: The voltage across an open circuit in a DC network is:
- Equal to the Thevenin voltage (Correct answer)
- Always zero
- Equal to the current times load resistance
- Undefined
Correct answer: Equal to the Thevenin voltage
The open-circuit voltage is precisely Vth because no current flows through the Thevenin resistance, causing no drop.
Question 5: A 5A current source has a 20Ω resistor in parallel. What is the open-circuit voltage across the terminals?
- 100V (Correct answer)
- 4V
- 25V
- 0V
Correct answer: 100V
Voc = IN × RN = 5A × 20Ω = 100V.
Question 6: If the current through a 47Ω resistor doubles, how does the power dissipated change?
- It quadruples (Correct answer)
- It doubles
- It halves
- It stays the same
Correct answer: It quadruples
P = I²R; if I doubles, P increases by a factor of 2² = 4 (quadruples).
Question 7: Which circuit analysis method assigns currents to independent loops rather than individual branches?
- Mesh analysis (Correct answer)
- Node voltage analysis
- Superposition
- Thevenin's theorem
Correct answer: Mesh analysis
Mesh (loop) analysis defines mesh currents circulating around independent loops, reducing the number of unknowns.
ISCET DC Circuit Analysis 5
What is the conductance of a 25Ω resistor?