Скачать или смотреть GCSE Physics - Efficiency | Energy & Power (2026/27 exams)

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** WHAT'S COVERED **
1. The concept of efficiency in energy transfers.
The difference between useful energy output and wasted energy.
Why devices are not 100% efficient.
2. How to calculate the efficiency of a device.
The formula for efficiency using energy input and useful energy output.
The formula for efficiency using power input and useful power output.
How to express efficiency as a decimal or a percentage.
3. Worked examples of efficiency calculations.
Comparing the efficiency of an incandescent bulb and an LED bulb.
Calculating the useful power output of a microwave given its efficiency.
4. Common mistakes and key principles related to efficiency.
How to spot an incorrect calculation (e.g., efficiency greater than 100%).
The link between efficiency and the conservation of energy.
An explanation of why devices producing heat can be considered 100% efficient.

** CHAPTERS **
0:00 Introduction
0:34 Useful & Wasted Energy
1:15 How to Calculate Efficiency
1:42 Worked Example: Lamp Efficiency
3:15 Common Mistakes When Calculating Efficiency
3:52 Worked Example: Microwave Power Output
4:35 Waste Energy & 100% Efficiency

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