| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Describe an experiment to show that a force acts on a current-carrying conductor in a magnetic field, including the effect of reversing: (a) the current (b) the direction of the field |
Learning Objective/s:
- Describe the experimental arrangement that demonstrates a magnetic force on a current‑carrying conductor.
- Explain how reversing the direction of the current changes the direction of the force.
- Explain how reversing the magnetic‑field direction changes the direction of the force.
- Predict how the magnitude of the force varies with current, magnetic‑field strength and conductor length.
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Materials Needed:
- U‑shaped magnet (or pair of bar magnets)
- Straight insulated copper wire (~0.20 m)
- Low‑friction pivot or lightweight wooden plank
- Adjustable DC power supply with ammeter
- Switch for reversing current direction
- Ruler or measuring scale
- Clamps/stand to hold the wire
- Safety goggles
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Introduction:
Begin with a quick demonstration of a compass needle moving when a current‑carrying wire is placed nearby to spark curiosity about magnetic forces. Review the formula F = I L B sinθ and ask students to predict what will happen if the current or field direction is changed. State that by the end of the lesson they will be able to design and interpret an experiment showing these effects.
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Lesson Structure:
- Do‑now (5'): Students answer a short set of questions on the right‑hand rule and the F = I L B relationship.
- Teacher set‑up & safety briefing (10'): Demonstrate the apparatus, point out safety precautions, and check that all groups have the required materials.
- Guided experiment (20'): Groups assemble the circuit, record the current, observe and measure wire deflection, then reverse the current and repeat.
- Field reversal (10'): Rotate the magnet 180°, repeat the measurements, and note the change in deflection direction.
- Data analysis & discussion (10'): Calculate proportionality, compare results for current and field reversals, and link observations to the cross‑product concept.
- Concept check (5'): Quick quiz or think‑pair‑share on why the force direction changes.
- Extension question (5'): Discuss how the experiment relates to galvanometers or motor operation.
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Conclusion:
Summarise that the magnetic force on a conductor depends on current, field strength, length, and orientation, and that reversing either the current or the field flips the force direction. Students complete an exit ticket stating one real‑world device that uses this principle. For homework, assign a short problem predicting deflection when the wire is placed at an angle to the field.
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