Exam-style question
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A transformer is 90% efficient and has a primary power input of 500 W. Calculate the useful power output of the transformer. Scenario focus: electric fields in a distinct A-Level Physics fields context; identify the field quantity, source, direction, and unit before selecting the answer.
Model answer
What a good answer should say
- The useful power output of the transformer is 450 W.
Explanation
Why this works
The correct answer is The useful power output of the transformer is 450 W.. This is correct for Magnetic fields because the stem is testing electric fields; the chosen option keeps the field quantity, source interaction, direction, and unit consistent.
The alternatives are weaker because they mix gravitational, electric, magnetic, orbital, or transformer ideas, or they attach the right number to the wrong physical meaning.
Common mistake
No common mistake is linked to this question yet.