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Conservation and efficiency
Apply the law of conservation of energy and calculate the percentage efficiency of devices to compare how well they use energy.
⏱ 19 min❓ 8 questions
What you'll be able to do
- ✔I can state the law of conservation of energy
- ✔I can calculate percentage efficiency from input and useful output energy
- ✔I can explain why no real device is 100% efficient and how efficiency can be improved
How this works
- 1Read the short explanations first — they teach you what you need before each question.
- 2Answer each question, then tap Check. A right answer moves you on automatically; if it's wrong, you'll see a friendly explanation of why.
- 3Finish all 3 steps to see your score — sign in and subscribe to unlock the full lesson and save it.
What's inside
8 questions and 1 quick teaching card, including:
- 🔢Number answer — Work out the answer and type the number.
👪Grown-up tip: sit alongside younger learners for the first few lessons. Read the questions together and chat about the explanations — that's where the real learning sticks.
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Curriculum: AC9S8U04