Efficiency (OCR GCSE Physics A (Gateway Science Suite)): Quizzes
📚Quizzes
Practise the questions
10 questions from this quiz
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Practise the questions
10 questions from this quiz
What does efficiency measure in a machine or device?
What does efficiency measure in a machine or device?
Ratio of useful work to energy supplied
What is the formula for efficiency using energy?
What is the formula for efficiency using energy?
Efficiency can also be calculated using which alternative quantities?
Efficiency can also be calculated using which alternative quantities?
Power input and output
A device uses J of energy and outputs J of useful energy. What is its efficiency?
A device uses J of energy and outputs J of useful energy. What is its efficiency?
20%
A motor uses J and outputs J usefully. Calculate the efficiency.
A motor uses J and outputs J usefully. Calculate the efficiency.
75%
Which method can increase efficiency by reducing waste?
Which method can increase efficiency by reducing waste?
Lubrication and thermal insulation
How can waste output be used to increase efficiency?
How can waste output be used to increase efficiency?
Recycling it as input energy
A bulb uses J but only J is light. What does efficiency tell us?
A bulb uses J but only J is light. What does efficiency tell us?
Only 20% of energy is useful
In a light bulb, which energy is considered 'useful output'?
In a light bulb, which energy is considered 'useful output'?
Light energy
If efficiency is calculated as , what is it as a percentage?
If efficiency is calculated as , what is it as a percentage?
40%