Electrical power and I-V characteristics

Electrical power and I-V characteristics Quiz

Spec 69–70 · Edexcel International A Level Physics: Quiz

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5 questions, one answer each

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  1. 1. A 12 V supply drives 2.0 A through a resistor. What is the power?

    • A. 6.0 W
    • B. 24 W
    • C. 48 W
    • D. 0.17 W

  2. 2. A 100 Ω resistor carries 0.30 A. What power does it dissipate?

    • A. 30 W
    • B. 3.0 W
    • C. 9.0 W
    • D. 0.0090 W

  3. 3. Which component has an I–V graph whose gradient increases with p.d. because its resistance falls as it heats?

    • A. Fixed resistor
    • B. Filament lamp
    • C. NTC thermistor
    • D. Diode in reverse

  4. 4. A diode is connected in the forward direction at 0.50 V. What is the current likely to be?

    • A. Large, as the diode obeys Ohm's law
    • B. Almost zero, as it is below the threshold p.d.
    • C. Equal to the reverse current
    • D. Infinite

  5. 5. Why is the current greater when a filament lamp is switched on than when it has been on for some time?

    • A. The cold filament has a lower resistance
    • B. The cold filament has a higher resistance
    • C. The supply p.d. is greater at switch-on
    • D. The ions in the filament vibrate more when cold

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