Fundamentals of Engineering Electrical Circuits and Systems 2 — Questions and Answers
Question 1: In a series RLC circuit at resonance, what is the impedance?
- Equal to R (purely resistive) (Correct answer)
- Zero
- Maximum
- Equal to the inductive reactance
Correct answer: Equal to R (purely resistive)
At resonance, inductive and capacitive reactances cancel (X_L = X_C), leaving only resistance Z = R.
Question 2: What is the power dissipated in a resistor of 10 Ω carrying a current of 3 A?
- 90 W (Correct answer)
- 30 W
- 900 W
- 3 W
Correct answer: 90 W
Power P = I²R = (3)² × 10 = 9 × 10 = 90 W.
Question 3: What type of filter passes low frequencies and attenuates high frequencies?
- Low-pass filter (Correct answer)
- High-pass filter
- Band-pass filter
- Band-stop filter
Correct answer: Low-pass filter
A low-pass filter allows frequencies below a cutoff frequency to pass while attenuating higher frequencies.
Question 4: Norton's equivalent circuit consists of:
- A current source I_N in parallel with a resistance R_N (Correct answer)
- A voltage source in series with a resistance
- Two current sources in parallel
- An inductor in parallel with a resistor
Correct answer: A current source I_N in parallel with a resistance R_N
Norton's theorem represents any linear network as a current source I_N in parallel with Norton resistance R_N.
Question 5: For a transformer with a turns ratio N₁:N₂ = 1:10, if the primary voltage is 120 V, what is the secondary voltage?
- 1,200 V (Correct answer)
- 12 V
- 120 V
- 10 V
Correct answer: 1,200 V
Transformer voltage ratio: V₂/V₁ = N₂/N₁ = 10/1, so V₂ = 120 × 10 = 1,200 V.
Question 6: What does the Bode plot display on its vertical and horizontal axes?
- Magnitude (dB) and phase (degrees) vs. log frequency (Correct answer)
- Time vs. amplitude
- Voltage vs. current
- Power vs. resistance
Correct answer: Magnitude (dB) and phase (degrees) vs. log frequency
A Bode plot shows gain in decibels and phase in degrees as functions of logarithmic frequency.
Fundamentals of Engineering Electrical Circuits and Systems 2
In a series RLC circuit at resonance, what is the impedance?