BEE FREE Bachelor of Electrical Engineering Electric Circuits Questions and Answers 2 — Questions and Answers
Question 1: A 10 V source is connected across two parallel resistors of 4 ohms and 12 ohms. What is the total current drawn from the source?
- 3.33 A (Correct answer)
- 2.50 A
- 1.67 A
- 4.00 A
Correct answer: 3.33 A
The equivalent resistance is (4×12)/(4+12) = 3 ohms, so I = 10/3 = 3.33 A.
Question 2: In a series RLC circuit at resonance, which of the following is true?
- The impedance is purely resistive (Correct answer)
- The impedance is at its maximum value
- The current is at its minimum value
- The phase angle is 90 degrees
Correct answer: The impedance is purely resistive
At resonance, inductive and capacitive reactances cancel, leaving only resistance.
Question 3: What is the time constant of a series RC circuit with R = 2 k-ohms and C = 50 microfarads?
- 0.1 seconds (Correct answer)
- 0.01 seconds
- 1 second
- 0.5 seconds
Correct answer: 0.1 seconds
The time constant tau = RC = 2000 × 50×10^-6 = 0.1 seconds.
Question 4: A node in an electric circuit has three currents: 5 A entering, 3 A entering, and one unknown current leaving. What is the unknown current?
- 8 A leaving (Correct answer)
- 2 A leaving
- 5 A leaving
- 3 A leaving
Correct answer: 8 A leaving
By Kirchhoff's Current Law, the sum of currents entering equals currents leaving, so the unknown current is 5 + 3 = 8 A.
Question 5: What is the maximum power transfer condition for a DC circuit with a source resistance of 50 ohms?
- Load resistance equals 50 ohms (Correct answer)
- Load resistance equals 100 ohms
- Load resistance equals 25 ohms
- Load resistance is infinite
Correct answer: Load resistance equals 50 ohms
Maximum power is transferred when the load resistance equals the source resistance.
Question 6: A capacitor of 100 microfarads is charged to 20 V. What is the energy stored in the capacitor?
- 0.02 J (Correct answer)
- 0.2 J
- 2 J
- 0.002 J
Correct answer: 0.02 J
Energy = 0.5 × C × V^2 = 0.5 × 100×10^-6 × 400 = 0.02 J.
BEE FREE Bachelor of Electrical Engineering Electric Circuits Questions and Answers 2
A 10 V source is connected across two parallel resistors of 4 ohms and 12 ohms.
What is the total current drawn from the source?