Slides
Lesson slides
Teaching slides for the lesson.
Open resourceLesson 03
Power & Efficiency
Relate power to the rate of transfer and efficiency to useful output.
Objectives
Lesson outcomes
- Define efficiency as the ratio of useful output to total input and use it in calculations.
- Define power as the rate of doing work or transferring energy.
- Use P = W/t to solve power problems.
- Derive and use P = Fv for motion at constant speed.
Syllabus
CIE 9702 syllabus points
5 linked
- 5.1.3 recall and understand that the efficiency of a system is the ratio of useful energy output from the system to the total energy input
- 5.1.4 use the concept of efficiency to solve problems
- 5.1.5 define power as work done per unit time
- 5.1.6 solve problems using P = W / t
- 5.1.7 derive P = Fv and use it to solve problems
Definitions
Required definitions
Power
work done per unit time.
Lesson Notes
Student guidance and lesson notes
Overview
Relate power to the rate of transfer and efficiency to useful output. Use this page to organise the main ideas, worked examples, and linked resources.
What You Need to Know
- Relate power to the rate of transfer and efficiency to useful output.
- Apply the definitions of power and efficiency to calculation and comparison questions.
- Use at least one worked example, observation, or practical link to make the idea concrete.
How to Work Through It
- Start with the prior knowledge, context, or recall questions for this lesson.
- Work through the main explanation, method, diagram, or calculation for this lesson.
- Complete the guided practice, discussion, calculations, or practical application.
- Review your learning with an exit prompt, short question, or summary task.
Check Your Understanding
- Can you answer a checkpoint question aligned to the main objective(s)?
- Can you give a short verbal, written, or numerical response that shows secure understanding?
Common Mistakes
- Watch out for the likely misconception, error, or weak step in this lesson.
- Use the comparison, model answer, or explanation that corrects it.
Next Steps
- Complete the homework, retrieval task, or resource revisit linked to this lesson.
- Note what you need to carry forward into the next lesson.
Lesson Resources
Materials for this lesson
Use these videos, slide decks, documents, or links to work through the lesson.
Worksheet
Power and Efficiency – Questions 3
Power and Efficiency – Questions 3
Open resourcePractical
Efficiency Practical
Efficiency Practical - Using an electric motor to raise a load
Open resourceWorksheet
Power and Efficiency - MCQs
Power and Efficiency - MCQs
Open resource