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This “Efficiency and Cost of Appliances” PowerPoint lesson is designed for AQA GCSE Physics students, covering how to calculate energy transfer in kilowatt-hours (kWh), determine electricity costs, and analyze efficiency in appliances. The lesson includes step-by-step explanations, worked examples, and real-world applications to help students develop problem-solving skills related to energy consumption and efficiency.
The lesson begins with a starter activity reviewing basic unit conversions, including grams to kilograms, meters to kilometers, and watts to kilowatts. It also prompts students to recall essential physics equations, such as the formulas for power, energy transfer, and efficiency. This ensures students have a strong foundation before learning how to calculate electricity costs and efficiency percentages.
Students first explore efficiency, understanding that it measures how well a device transfers energy usefully. They learn that no device is 100% efficient, as some energy is always wasted, often as heat. The lesson introduces the efficiency equations: efficiency = useful energy output / total energy input and efficiency = useful power output / total power input. Students practice calculating efficiency using given input and output values, converting between decimal and percentage forms, and analyzing why higher efficiency reduces energy waste and cost.
Next, the lesson covers energy transfer and electricity costs. Students learn how to calculate energy consumption in kilowatt-hours (kWh) rather than joules, making energy usage easier to compare on electricity bills. The equation used is: E=P×t where E is energy (kWh), P is power (kW), and t is time (hours). Students apply this equation to real-world scenarios, such as calculating the energy consumption of a washing machine, microwave, and heater over different time periods.
To determine the cost of using electrical appliances, students use the equation: Cost §=Power (kW)×Time (hours)×Cost per Unit §. Worked examples guide students through calculating the total cost of running household appliances, reinforcing the importance of energy efficiency in reducing electricity bills.
This editable PowerPoint (.pptx) file is designed for AQA GCSE Physics students. Updated in February 2025, it includes structured explanations, interactive problem-solving exercises, and real-world applications, making it an essential resource for teaching efficiency, energy transfer, and electricity costs in GCSE Physics.
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