Question detail
If a light bulb uses 240 J of energy in 2 seconds, what is its power?
Try the question, check the answer, then read the explanation to understand the curriculum point.
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. 100 W
- B. 120 W
- C. 140 W
- D. 150 W
Answer
120 W
Explanation
The correct option is "120 W". 120 W is right because it directly matches Power: Rearrange power equations to calculate energy transferred, work done or time.. 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
Common Mistake in Rearranging Power Equations
Students often confuse the formulas for power, energy transferred, and work done, leading to incorrect rearrangements.
To correctly rearrange the power equations, remember that power (P) can be calculated as P = energy transferred (E) / time (t) or P = work done (W) / time (t). Ensure you isolate the variable you need by multiplying or dividing appropriately.
Related flashcards
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