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AC Circuit Analysis & Power Flashcards

7 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 AC Circuit Analysis & Power flashcards as text
  1. In a three-phase balanced system, what is the phase voltage if the line voltage is 208 V?

    Answer: 120 V

    Phase voltage = Line voltage / √3 = 208 / 1.732 ≈ 120 V in a wye (Y) configuration.

  2. What does a leading power factor indicate about a circuit's load?

    Answer: The load is predominantly capacitive

    A leading power factor means current leads voltage, which is the characteristic behavior of a predominantly capacitive load.

  3. What is the formula for inductive reactance (XL)?

    Answer: XL = 2πfL

    Inductive reactance XL = 2πfL, where f is frequency in Hz and L is inductance in henries.

  4. A 10 Ω resistor and a 10 Ω inductive reactance are connected in series. What is the circuit's power factor?

    Answer: 0.707

    PF = cos(θ) = R/Z = 10/√(10²+10²) = 10/14.14 ≈ 0.707.

  5. In AC circuit analysis, what does the imaginary component of an impedance phasor represent?

    Answer: Net reactance (inductive or capacitive)

    The imaginary component of impedance (jX) represents net reactance, either inductive (+jX) or capacitive (−jX).

  6. What effect does increasing the series resistance in an RLC resonant circuit have on the selectivity?

    Answer: Decreases selectivity (widens bandwidth)

    Higher resistance lowers the Q factor (Q = XL/R), which widens the bandwidth and reduces selectivity.

  7. Which of the following correctly describes apparent power in an AC circuit?

    Answer: The product of RMS voltage and RMS current

    Apparent power S = VRMS × IRMS (in VA), representing the total power supplied regardless of phase angle.