Efficiency (OCR GCSE Physics A, Combined (Gateway Science Suite)): Quizzes

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Efficiency
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What is efficiency?

Ratio of useful output to total input

What is the formula for efficiency using energy?

useful energy outputtotal energy input\frac{useful\ energy\ output}{total\ energy\ input}

What is the formula for efficiency using power?

useful power outputtotal power input\frac{useful\ power\ output}{total\ power\ input}

A motor uses 5050 J of energy and outputs 1010 J of useful energy. What is its efficiency?

20%

A device has 200200 J input and 8080 J useful output. Calculate its efficiency.

40%

Which method can increase efficiency?

Reducing waste output

How can recycling waste output increase efficiency?

Absorbing thermal waste as input energy

In the efficiency formula, what does the denominator represent?

Total energy input

Which is an example of reducing waste output?

Lubrication

A bulb uses 100100 J and gives 2020 J of light. What is its efficiency?

20%

Explore OCR GCSE Physics A, Combined (Gateway Science Suite) Revision Notes by Topics

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