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Energy

Quick questions on Power and efficiency - CCEA GCSE Physics

4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.

What is power?
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A more powerful device transfers the same energy in less time, or more energy in the same time. A 2000 W2000\ \text{W} kettle transfers energy twice as fast as a 1000 W1000\ \text{W} one.
What is q1?
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State the equation for power and the unit of power. [2 marks]
What is q2?
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A device transfers 1200 J1200\ \text{J} in 4.0 s4.0\ \text{s}. Find its power. [2 marks]
What is q3?
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A machine takes in 500 J500\ \text{J} and usefully transfers 350 J350\ \text{J}. Find its efficiency as a percentage. [2 marks]

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