Practice Test Geeks(PC) Professional Electrical Contractor Practice Test
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General Theory and Calculations Flashcards

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

Read the first 7 General Theory and Calculations flashcards as text

  1. A 10 kVA transformer operates at 0.85 power factor. What is its real power output in kW?

    Answer: 8.5 kW

    P = S × PF = 10 kVA × 0.85 = 8.5 kW.

  2. Which of the following best describes reactive power (VAR)?

    Answer: Power stored and returned by inductive or capacitive elements

    Reactive power represents energy oscillating between the source and reactive elements (inductors/capacitors) without being consumed.

  3. What is the impedance of a series circuit with R = 5Ω, XL = 12Ω, and XC = 0Ω?

    Answer: 13 Ω

    Z = √(R² + XL²) = √(25 + 144) = √169 = 13 Ω.

  4. An electrical service carries 200A at 240V single-phase. What is the maximum kVA demand?

    Answer: 48 kVA

    S = V × I = 240 × 200 = 48,000 VA = 48 kVA.

  5. Which statement correctly describes Lenz's Law?

    Answer: An induced current opposes the change in magnetic flux that caused it

    Lenz's Law states the induced EMF always drives a current that opposes the change in flux (conservation of energy).

  6. A capacitor-start motor uses a run capacitor to improve efficiency. What does the run capacitor primarily improve?

    Answer: Power factor and running efficiency

    A run capacitor remains in the circuit during normal operation to correct power factor and improve running efficiency.

  7. Using the voltage divider rule, what is the voltage across a 4Ω resistor in series with an 8Ω resistor connected across 120V?

    Answer: 40 V

    V_4Ω = 120 × (4 / (4+8)) = 120 × (1/3) = 40 V.