| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Describe the effect on the magnetic field around straight wires and solenoids of changing the magnitude and direction of the current |
Learning Objective/s:
- Describe how magnetic field strength around a straight wire varies with current magnitude and distance.
- Explain the effect of reversing current direction on magnetic field orientation for straight wires and solenoids.
- Calculate the magnetic field inside a solenoid using B = μ₀ n I and predict changes when current changes.
- Compare magnetic field patterns of straight conductors and solenoids when the current magnitude is altered.
- Apply the right‑hand rule to determine field direction in different scenarios.
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Materials Needed:
- Projector and screen
- Printed diagram handouts of wires and solenoids
- Adjustable DC power supply
- Straight copper wire and a coil (solenoid) setup
- Compass or magnetic field sensor
- Worksheets and calculators
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Introduction:
Begin with a quick demonstration of a compass deflecting near a live wire to spark curiosity. Review students’ prior knowledge of the right‑hand rule and the formula B = μ₀I/2πr for a straight conductor. State that by the end of the lesson they will be able to predict how both magnitude and direction of current reshape magnetic fields around wires and solenoids.
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Lesson Structure:
- Do‑now (5 min): Quick quiz on right‑hand rule and field‑strength formula.
- Mini‑lecture (10 min): Summarise theory for straight wires and solenoids, emphasising B ∝ I and direction reversal.
- Demo 1 – Straight wire (8 min): Vary current using the power supply, observe compass deflection, discuss proportional change.
- Demo 2 – Solenoid (8 min): Show uniform internal field, flip current direction, note pole swap.
- Guided practice (10 min): Students work in pairs on worksheet calculations for different I values and predict field directions.
- Check for understanding (5 min): Exit‑ticket question – “If the current in a solenoid is doubled, how does the internal field change?”
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Conclusion:
Recap the linear relationship between current magnitude and field strength and the role of the right‑hand rule for direction. Collect exit tickets and remind students to complete the homework worksheet that asks them to sketch field lines for given current changes. Assign a short online quiz for reinforcement.
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