Fundamentals of Engineering Electrical Circuits and Systems 1 — Questions and Answers
Question 1: What is Ohm's Law?
- V = IR (Correct answer)
- V = I/R
- V = I²R
- V = IR²
Correct answer: V = IR
Ohm's Law states that voltage equals current times resistance: V = IR.
Question 2: Three resistors of 6 Ω, 3 Ω, and 2 Ω are connected in parallel. What is the equivalent resistance?
- 1 Ω (Correct answer)
- 11 Ω
- 3.67 Ω
- 2 Ω
Correct answer: 1 Ω
1/R_eq = 1/6 + 1/3 + 1/2 = 1/6 + 2/6 + 3/6 = 6/6 = 1, so R_eq = 1 Ω.
Question 3: Kirchhoff's Voltage Law (KVL) states that:
- The sum of all voltages around any closed loop is zero (Correct answer)
- The sum of currents entering a node equals those leaving
- Voltage is proportional to resistance
- Power dissipated equals voltage squared divided by resistance
Correct answer: The sum of all voltages around any closed loop is zero
KVL is based on conservation of energy: the algebraic sum of all voltage drops around a closed loop equals zero.
Question 4: What is the impedance of an ideal capacitor C at angular frequency ω?
- 1/(jωC) (Correct answer)
- jωC
- jωL
- R + jωL
Correct answer: 1/(jωC)
The impedance of a capacitor is Z_C = 1/(jωC), which decreases with increasing frequency.
Question 5: In an AC circuit, power factor is defined as:
- cos(θ), where θ is the phase angle between voltage and current (Correct answer)
- The ratio of reactive power to apparent power
- The ratio of voltage to current
- The ratio of resistance to impedance
Correct answer: cos(θ), where θ is the phase angle between voltage and current
Power factor = cos(θ), where θ is the phase angle between voltage and current; it ranges from 0 to 1.
Question 6: What does a Thevenin equivalent circuit consist of?
- A voltage source V_th in series with a resistance R_th (Correct answer)
- A current source in parallel with a resistance
- Two voltage sources in series
- A capacitor in series with a resistor
Correct answer: A voltage source V_th in series with a resistance R_th
A Thevenin equivalent represents a linear network as a single voltage source V_th in series with Thevenin resistance R_th.
Fundamentals of Engineering Electrical Circuits and Systems 1
What is Ohm's Law?