| Lesson Plan |
| Grade: Year 12 |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: explain the origin of the forces between current-carrying conductors and determine the direction of the forces |
Learning Objective/s:
- Describe how a current‑carrying conductor creates a circular magnetic field.
- Explain the Lorentz force law for a current element and its role in conductor interactions.
- Determine the direction of the force between two parallel conductors using the right‑hand rule.
- Calculate the magnitude of the force between parallel conductors with F = μ₀I₁I₂L/(2πd).
- Connect the force definition to the operational definition of the ampere.
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Materials Needed:
- Projector and screen
- Whiteboard and markers
- Printed diagrams of the right‑hand rule
- Worksheet with force‑calculation problems
- Handout on the definition of the ampere
- Two insulated wires, power supply, and a ruler for a live demonstration
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Introduction:
Imagine two wires that either pull together or push apart simply because of the direction of the current flowing through them. You already know that a current produces a magnetic field and that the right‑hand rule tells you its direction. Today you will predict the force direction and compute its size, and you will see how this underpins the definition of the ampere.
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Lesson Structure:
- Do‑now (5'): Quick quiz on the magnetic field direction around a straight wire.
- Mini‑lecture (10'): Derive B = μ₀I/(2πr) and introduce F = I L × B.
- Demonstration (10'): Power two parallel wires; observe attraction or repulsion and relate to the right‑hand rule.
- Guided practice (15'): Worksheet – calculate force magnitude for given I₁, I₂, L, d and state the direction.
- Group activity (10'): Students sketch field lines and explain the origin of the force between the conductors.
- Check for understanding (5'): Exit ticket – state the rule for force direction between parallel conductors.
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Conclusion:
We reviewed how each conductor’s magnetic field creates a force on the other and how the right‑hand rule determines its direction. Your exit ticket shows you can predict attraction or repulsion, and the homework – additional force‑calculation problems and a short paragraph on the ampere definition – will reinforce today’s learning.
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