| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Describe a simple form of a.c. generator (rotating coil or rotating magnet) and the use of slip rings and brushes where needed |
Learning Objective/s:
- Describe the principle of electromagnetic induction in a simple AC generator.
- Explain how rotating a coil or rotating a magnet produces an alternating emf.
- Identify the function of slip rings and brushes in a rotating‑coil generator.
- Compare rotating‑coil and rotating‑magnet generators regarding construction and need for slip rings.
- Apply the emf formula to calculate the peak voltage for given parameters.
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Materials Needed:
- Projector and screen for diagrams
- Whiteboard and markers
- Printed handouts of generator diagrams
- Simple model of a rotating‑coil generator or virtual simulation
- Slip‑ring and brush demonstration kit (optional)
- Worksheet with calculation problems
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Introduction:
Begin with a quick demonstration of a hand‑cranked flashlight to spark curiosity about how mechanical motion can create electricity. Review Faraday’s law and the concept of changing magnetic flux that students learned previously. Explain that today they will explore two simple AC generator designs and discover why slip rings and brushes are required in one but not the other.
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Lesson Structure:
- Do‑now (5') – students answer a short question on Faraday’s law on the board.
- Mini‑lecture (10') – present the rotating‑coil generator, show diagram, discuss components and role of slip rings/brushes.
- Demonstration (8') – use the model or simulation to rotate the coil and observe alternating voltage on a meter.
- Group activity (12') – students draw circuit diagrams for both generator types and label where slip rings are needed.
- Comparison discussion (8') – fill a Venn diagram comparing rotating‑coil and rotating‑magnet generators.
- Practice problem (7') – solve the exam‑style calculation individually, then check answers.
- Recap quiz (5') – rapid‑fire true/false statements to check understanding.
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Conclusion:
Summarise that alternating emf arises from a changing magnetic flux, whether the coil or the field moves, and that slip rings are only needed when the emf‑carrying part rotates. Ask students to write one key point on a sticky note as an exit ticket. For homework, assign a worksheet requiring calculation of peak emf for different generator parameters.
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