Question detail

If a device transfers 100 joules of energy in 5 seconds, what is its power rating?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Energy changes in a system, and the ways energy is stored before and after such changes

Question

A. 20 watts
B. 25 watts
C. 50 watts
D. 100 watts

Answer

20 watts

Explanation

The correct option is "20 watts". 20 watts is right because it directly matches Power: Compare devices with different power ratings using energy-transfer examples.. 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

Power Ratings Comparison

Students often confuse power ratings with energy transferred, thinking that a higher power rating means more energy is transferred overall, rather than in a given time.

Clarify that power is the rate of energy transfer; a device with a higher power rating transfers energy faster, not necessarily more energy overall.

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