Power and Efficiency (Leaving Cert Physics): Quizzes
📚Quizzes
Practise the questions
12 questions from this quiz
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Practise the questions
12 questions from this quiz
What does power measure in physics?
What does power measure in physics?
The rate of doing work
Which formula correctly represents power?
Which formula correctly represents power?
What does 1 watt equal?
What does 1 watt equal?
1 joule per second
Who is the watt named after?
Who is the watt named after?
James Watt
A weightlifter does 4410 J of work in 30 s. What is their average power in watts?
A weightlifter does 4410 J of work in 30 s. What is their average power in watts?
147 W
How much power does a typical LED bulb use?
How much power does a typical LED bulb use?
7-10 watts
What does efficiency measure?
What does efficiency measure?
How well input converts to useful output
Which formula correctly calculates percentage efficiency?
Which formula correctly calculates percentage efficiency?
What is the efficiency of a 60W incandescent bulb that produces 3W of light?
What is the efficiency of a 60W incandescent bulb that produces 3W of light?
5%
An LED bulb produces 3W of light using 7W input. What is its efficiency?
An LED bulb produces 3W of light using 7W input. What is its efficiency?
42.9%
A car engine is 30% efficient with 105 kW input. What is the useful power output in kW?
A car engine is 30% efficient with 105 kW input. What is the useful power output in kW?
31.5 kW
What percentage of fuel energy becomes waste heat in a typical petrol car engine?
What percentage of fuel energy becomes waste heat in a typical petrol car engine?
70%