Question detail
If a device has a useful energy output of 150 J and a total energy input of 200 J, what is its efficiency expressed as a percentage?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Conservation and dissipation of energy
Question
If a device has a useful energy output of 150 J and a total energy input of 200 J, what is its efficiency expressed as a percentage?
Answer
The efficiency is 75%.
Explanation
This question requires students to apply the efficiency formula to calculate the efficiency as a percentage. It tests their understanding of how to convert the efficiency value into a percentage format, reinforcing their application skills. This answer is linked to Efficiency because it applies the learning objective: Recall and apply both efficiency equations.. It shows the Physics relationship clearly and keeps energy, power, work done and efficiency terms distinct where they appear.
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.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.