Energy Transfers
Overview
Switch on an old filament lamp and about nine tenths of the electricity you are paying for ends up warming the ceiling. The energy did not vanish and it was not destroyed; it simply went somewhere you did not want it. Tracking where energy goes is one of the most powerful habits in physics.
This lesson names the eight stores energy can sit in and the four pathways it travels by, states the principle of conservation of energy, and shows you how to calculate an efficiency and read the whole story of a device off a single Sankey diagram.
Objectives
- Describe energy transfers involving energy stores (chemical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic, nuclear) and energy transfers (mechanically, electrically, by heating, by radiation)
- Use the principle of conservation of energy
- Know and use the relationship between efficiency, useful energy output and total energy output
- Describe a variety of everyday and scientific devices and situations, explaining the transfer of the input energy, including their representation by Sankey diagrams
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Energy Transfers. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which of the following is an energy store, not a pathway? A) Electrical B) Heating C) Elastic D) Radiation Answer: C
- A device takes in 250 J and produces 50 J of useful output. Its efficiency is: A) 5% B) 20% C) 50% D) 200% Answer: B
- The principle of conservation of energy states that energy: A) is always destroyed by friction B) cannot be created or destroyed, only transferred C) can be created in a power station D) is used up when a device is switched on Answer: B
- In a Sankey diagram, the width of each arrow represents: A) the time taken B) the temperature C) the amount of energy D) the efficiency Answer: C
- Energy stored in a stretched elastic band is in the: A) chemical store B) elastic store C) thermal store D) nuclear store Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Practice Mock Questions
Want to practice mock questions on Energy Transfers? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
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