BEE Electric Circuit Analysis 3 — Questions and Answers
Question 1: Norton's theorem converts a circuit to an equivalent:
- Voltage source in series with Rth
- Current source in parallel with Rth (Correct answer)
- Voltage source in parallel with Rth
- Current source in series with Rth
Correct answer: Current source in parallel with Rth
Norton's equivalent consists of a short-circuit current source (IN) in parallel with the Thevenin resistance (Rth).
Question 2: In mesh analysis, mesh currents are defined to flow in which direction by convention?
- Counter-clockwise
- Clockwise (Correct answer)
- Either direction, but must be consistent
- Alternating directions per mesh
Correct answer: Clockwise
By convention, mesh currents are assigned to flow clockwise in each mesh, though counter-clockwise is also valid if consistently applied.
Question 3: A 10 Ω resistor carries 2 A. What power does it dissipate?
- 20 W
- 40 W (Correct answer)
- 5 W
- 100 W
Correct answer: 40 W
P = I²R = (2)² × 10 = 40 W.
Question 4: Which of the following is the correct expression for the quality factor Q of a series RLC circuit?
- Q = R/(ωL)
- Q = ωL/R (Correct answer)
- Q = ωRC
- Q = 1/(ωRC)
Correct answer: Q = ωL/R
For a series RLC circuit, Q = ωₒL/R = (1/R)√(L/C), indicating the sharpness of resonance.
Question 5: KVL (Kirchhoff's Voltage Law) is based on the principle of conservation of:
- Charge
- Energy (Correct answer)
- Power
- Current
Correct answer: Energy
KVL states that the algebraic sum of voltages around any closed loop is zero, which is a direct consequence of energy conservation.
Question 6: In a purely capacitive AC circuit, current leads voltage by:
- 0°
- 90° (Correct answer)
- 180°
- 45°
Correct answer: 90°
In a purely capacitive circuit, current leads the voltage by 90° because the capacitor charges in response to the applied voltage.
Question 7: What is the Thevenin resistance seen from terminals A-B when all independent sources are turned off?
- It equals the short-circuit current
- It is the resistance measured with sources replaced by their internal resistances (Correct answer)
- It equals the open-circuit voltage
- It is always zero
Correct answer: It is the resistance measured with sources replaced by their internal resistances
Rth is found by deactivating all independent sources (voltage sources → short, current sources → open) and measuring the resistance at the terminals.
BEE Electric Circuit Analysis 3
Norton's theorem converts a circuit to an equivalent: