Ages 12–13🔬 Science6 verified questions on this shelf
Efficiency, Sankey diagrams, and work done
Calculate energy efficiency as the ratio of useful output energy to total input energy, construct and interpret Sankey diagrams, and calculate work done using work = force × distance
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Question 1 of 3
A small electric heater uses 1200 J of electrical energy. Of this, 900 J is transferred to the water it heats, and the remaining energy is lost as heat to the surroundings. What is the efficiency of the heater expressed as a percentage?
Question 2 of 3
A small electric heater uses 1200 J of electrical energy. Of this energy, 300 J is used to heat the water (the useful output), and the rest is lost as heat to the surroundings. What is the energy efficiency of the heater, expressed as a percentage?
Question 3 of 3
A heater uses 500 J of electrical energy, and 150 J of that energy is transferred as useful heat to warm a room. What is the energy efficiency of the heater expressed as a percentage?
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