Science
Energy
Conceptual
12–13 yrs
Power: watts and energy per second
功率：瓦特与每秒能量
Description
Define power as the rate of energy transfer (power = energy ÷ time, measured in watts), and compare energy transfer rates in different everyday contexts
Mastery Evidence
- States the definition of power and gives its unit (watt)
- Uses P = E/t to calculate power, energy, or time given the other two quantities
- Compares the power ratings of common appliances and explains what the rating means
- Explains why a higher-powered device does the same job faster but uses more energy
Assessment Prompt
If your child was comparing a 100 W light bulb with a 10 W LED, could they explain what those numbers mean and calculate how much energy each uses in an hour?
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