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 transformer has a 2:1 turns ratio (primary:secondary). If the primary voltage is 240V, what is the secondary voltage?

    Answer: 120 V

    V_S = V_P × (N_S/N_P) = 240 × (1/2) = 120 V.

  2. What does the term 'skin effect' describe in electrical conductors carrying AC current?

    Answer: Concentration of current near the conductor surface, increasing effective resistance

    Skin effect causes AC current to concentrate near the outer surface of a conductor, reducing effective cross-section and increasing resistance.

  3. If a 120V outlet supplies a 1,440W load, what is the current draw?

    Answer: 12 A

    I = P / V = 1,440 / 120 = 12 A.

  4. Which law states that the algebraic sum of currents entering and leaving a node equals zero?

    Answer: Kirchhoff's Current Law

    Kirchhoff's Current Law (KCL) states that the sum of currents at any junction equals zero (charge conservation).

  5. A 3-phase delta-connected load has a phase resistance of 30Ω per leg. Line voltage is 208V. What is the line current?

    Answer: 11.97 A

    Phase current = V_line / R = 208/30 ≈ 6.93 A; line current = √3 × 6.93 ≈ 11.97 A.

  6. What is the effect of doubling the cross-sectional area of a conductor on its resistance?

    Answer: Resistance is halved

    R = ρL/A; doubling A halves resistance because resistance is inversely proportional to cross-sectional area.

  7. What is the phase angle of a circuit with 30Ω resistance and 40Ω total reactance (net inductive)?

    Answer: 53.13°

    θ = arctan(X/R) = arctan(40/30) = arctan(1.333) ≈ 53.13°.