Capacitor charge and discharge

Capacitor charge and discharge Quiz

Spec 118–120 · Edexcel A-Level Physics: Quiz

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5 questions, one answer each

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  1. 1. A 100 μF capacitor discharges through a 20 kΩ resistor. What is the time constant?

    • A. 2.0 s
    • B. 0.20 s
    • C. 5.0 s
    • D. 2.0 × 10⁻⁹ s

  2. 2. After a time equal to one time constant, what fraction of its initial value remains on a discharging capacitor?

    • A. 0.50
    • B. 0.37
    • C. 0.10
    • D. 0.63

  3. 3. The time constant of a discharge circuit is 5.0 s. R is doubled and C is halved. What is the new time constant?

    • A. 2.5 s
    • B. 10 s
    • C. 20 s
    • D. 5.0 s

  4. 4. A graph of ln V against t for a discharging capacitor is a straight line. What is its gradient?

    • A. RC
    • B. −RC
    • C. 1/RC
    • D. −1/RC

  5. 5. A capacitor discharges through a resistor. Which graph shape describes the current against time?

    • A. A straight line falling to zero
    • B. A curve falling steeply at first and then more slowly
    • C. A curve rising steeply at first and then levelling off
    • D. A horizontal line

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