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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“If your child heard that a light bulb is 10% efficient and uses 60 J of energy, could they work out how much of that energy actually becomes light — and where the rest goes?”
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- Activity. 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
What to notice. Calculates efficiency as a percentage from given input and useful output energy values • Draws a Sankey diagram to represent energy transfers in a device, with arrow widths proportional to energy amounts • Uses W = Fd to calculate work done when a force moves through a distance • Identifies which energy transformations in a Sankey diagram are useful and which are wasted
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If your child heard that a light bulb is 10% efficient and uses 60 J of energy, could they work out how much of that energy actually becomes light — and where the rest goes?
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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Check understanding
- Calculates efficiency as a percentage from given input and useful output energy values
- Draws a Sankey diagram to represent energy transfers in a device, with arrow widths proportional to energy amounts
- Uses W = Fd to calculate work done when a force moves through a distance
- Identifies which energy transformations in a Sankey diagram are useful and which are wasted
“If your child heard that a light bulb is 10% efficient and uses 60 J of energy, could they work out how much of that energy actually becomes light — and where the rest goes?”
Curriculum record
- Type
- Procedural
- Subject
- Science
- Domain
- Energy
- Age range
- Ages 12–13
Standards