Question detail
A light bulb uses 60 J of electrical energy to produce 54 J of light energy. Calculate the efficiency of the light bulb.
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
A light bulb uses 60 J of electrical energy to produce 54 J of light energy. Calculate the efficiency of the light bulb.
Answer
0.9 or 90%
Explanation
The efficiency is calculated by dividing the useful energy output by the total energy input, which tests the understanding of energy efficiency concepts. This answer is linked to Energy transfers in a system because it applies the learning objective: State that energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.. It shows the Physics relationship clearly and keeps energy, power, work done and efficiency terms distinct where they appear.
Common mistake
Misunderstanding Energy Conservation
Students often think that energy can be created or destroyed in a system.
Remember that energy cannot be created or destroyed; it can only be transferred, stored, or dissipated.
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