Exam-style question
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A battery supplies an emf of 12 V. If the energy supplied to 3 C of charge is required, calculate the energy supplied by the battery.
Model answer
What a good answer should say
- The energy supplied can be calculated using the formula E = emf × Q.
- Substituting the values, E = 12 V × 3 C = 36 J.
- Therefore, the energy supplied by the battery is 36 J.
Explanation
Why this works
The correct answer is The energy supplied can be calculated using the formula E = emf × Q. This is correct because it applies the Current electricity idea named in the question, using the required quantities and units rather than mixing current, charge, potential difference, resistance, power, or energy.
The other options are less suitable because they use the wrong electrical quantity, an incompatible unit, or a rule from a different circuit context.
Common mistake
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