AQA · Physics · 8463

GCSE Physics: Power

Electricity · AQA GCSE Physics (8463), specification point 4.2.4.1. Cards are generated from the exam board's own specification for "Power", and every card links back to the page it came from. Specification © AQA — used with attribution.

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  1. What is the equation linking power, potential difference and current?

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    P = V I (power = potential difference × current).

  2. What is the equation linking power, current and resistance?

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    P = I² R (power = current² × resistance).

  3. Electrical power = potential difference × ?.

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    current

  4. Electrical power = current² × ?.

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    resistance

  5. What is the SI unit of electrical power?

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    The watt (W).

  6. What is the unit of potential difference?

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    The volt (V).

  7. What is the unit of electric current?

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    The ampere (A), commonly called the amp.

  8. What is the unit of electrical resistance?

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    The ohm (Ω).

  9. Why does doubling the current through a fixed resistor quadruple the power?

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    Because P = I² R — power is proportional to the square of the current, so 2× current gives 2² = 4× power.

  10. A 12 V motor draws 2 A. What is its power?

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    24 W (P = V I = 12 × 2).

  11. A 3 A current flows through a 10 Ω resistor. What power is dissipated?

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    90 W (P = I² R = 3² × 10).

  12. What does the power of a circuit device tell you about energy transfer?

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    The rate at which energy is transferred — how much energy is transferred per second.

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