Practice Test Geeks(PC) Professional Electrical Contractor Practice Test
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Electrical Theory & Principles 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 Electrical Theory & Principles flashcards as text

  1. In an AC circuit, the opposition to current flow caused by an inductor is called:

    Answer: Inductive reactance

    Inductive reactance (XL = 2πfL) is the opposition an inductor presents to AC current, measured in ohms.

  2. Power factor in an AC circuit is defined as the ratio of:

    Answer: True power to apparent power

    Power factor = True Power (W) ÷ Apparent Power (VA), ranging from 0 to 1.

  3. A single-phase transformer has a primary winding of 480V with 400 turns and a secondary with 100 turns. What is the secondary voltage?

    Answer: 120V

    Vs = Vp × (Ns/Np) = 480 × (100/400) = 480 × 0.25 = 120V.

  4. In an AC circuit containing only resistance, the voltage and current are:

    Answer: In phase

    Pure resistive loads cause no phase shift — voltage and current reach their peaks simultaneously.

  5. What happens to inductive reactance (XL) when the frequency of the applied AC voltage doubles?

    Answer: It doubles

    XL = 2πfL; doubling frequency doubles XL since inductance L remains constant.

  6. Apparent power in an AC circuit is measured in:

    Answer: Volt-Amperes (VA)

    Apparent power (S = V × I) is expressed in volt-amperes (VA) to distinguish it from true power in watts.

  7. A step-up transformer increases voltage. To maintain conservation of energy, it must correspondingly:

    Answer: Decrease current on the secondary side

    Since power = V × I must be conserved (in an ideal transformer), increasing voltage requires a proportional decrease in current.