Question detail
Which equation correctly represents the efficiency of a system that converts 500 J of input energy into 350 J of useful output energy?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Conservation and dissipation of energy
Question
- A. Efficiency = (500 J ÷ 350 J) × 100
- B. Efficiency = (350 J ÷ 500 J) × 100
- C. Efficiency = (500 J × 350 J) ÷ 100
- D. Efficiency = (350 J + 500 J) ÷ 100
Answer
Efficiency = (350 J ÷ 500 J) × 100
Explanation
The correct option is "Efficiency = (350 J ÷ 500 J) × 100". Efficiency = (350 J ÷ 500 J) × 100 is right because it directly matches Efficiency: Recall and apply both efficiency equations.. The other options are less suitable because they change the required Physics relationship, confuse the relevant energy store or use a distractor that does not answer the question.
Common mistake
Confusing Efficiency Equations
Students often confuse the two efficiency equations, using useful energy output for total power input instead of total energy input.
Remember that efficiency can be calculated using either useful energy output divided by total energy input or useful power output divided by total power input. Always check which type of input is required.
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