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OAR Mechanical Comprehension: Electricity Flashcards

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

Read the first 7 OAR Mechanical Comprehension: Electricity flashcards as text

  1. A wire carries 2A of current. How many coulombs of charge pass through in 30 seconds?

    Answer: 60C

    Charge Q = I × t = 2A × 30s = 60C.

  2. What does increasing the cross-sectional area of a conductor do to its resistance?

    Answer: Decreases resistance

    A larger cross-section provides more parallel paths for electrons, lowering resistance like widening a pipe reduces flow resistance.

  3. A diode allows current to flow in which direction?

    Answer: Only from anode to cathode

    A diode conducts current from anode to cathode (conventional current direction) and blocks reverse flow.

  4. What is the power factor in a purely resistive AC circuit?

    Answer: 1

    In a purely resistive circuit, voltage and current are in phase, giving a power factor of 1 (unity).

  5. Which law states that the total current entering a junction equals the total current leaving it?

    Answer: Kirchhoff's Current Law

    Kirchhoff's Current Law (KCL) states that charge conservation requires all current entering a node to equal all current leaving it.

  6. A step-up transformer increases voltage. What happens to the current on the secondary side (assuming ideal transformer)?

    Answer: Current decreases proportionally

    An ideal transformer conserves power (P = VI), so if voltage increases, current must decrease by the same ratio.

  7. What is the equivalent capacitance of two 4μF capacitors connected in series?

    Answer: 2μF

    For capacitors in series, 1/C = 1/4 + 1/4 = 2/4, so C = 2μF.