Lesson Plan

• Describe how magnetic field strength varies with current, distance and geometry for straight wires and solenoids.
• Explain the effect of number of turns, core material and solenoid length on the field inside a solenoid.
• Apply the right‑hand rule to predict the direction of the magnetic field around a current‑carrying conductor.
• Compare qualitative trends for straight wires and solenoids and relate them to practical design choices.

• Projector or interactive whiteboard
• Power supply with insulated copper wire (straight segment)
• Solenoid coil with removable ferromagnetic core
• Ammeter and ruler (measure current and distance)
• Compass or magnetic field sensor
• Worksheet with diagram prompts
• Tangent galvanometer (optional demonstration)

Begin with a quick visual of a compass needle deflecting near a current‑carrying wire to spark curiosity. Review that students already know a current produces a magnetic field and that field lines form circles around the wire. State that by the end of the lesson they will be able to articulate the qualitative factors that strengthen or weaken those fields for both straight wires and solenoids.

1. Do‑now (5'): Students answer three short questions on magnetic fields from the previous lesson.
2. Mini‑lecture (10'): Review the right‑hand rule and introduce the qualitative relationships for a straight wire (current ↑ → B ↑; distance ↑ → B ↓).
3. Demonstration (10'): Use a powered straight wire and a compass; vary current and distance, students note observations.
4. Group activity (12'): Work with a solenoid, change current, number of turns, and insert/remove a ferromagnetic core; record how the field changes.
5. Guided analysis (8'): Complete the summary table (increase/decrease factors) collaboratively on the board.
6. Check for understanding (5'): Exit ticket – list two ways to increase field strength for a straight wire and for a solenoid.

Recap the key qualitative trends and how they guide the design of electromagnets. Collect exit tickets to gauge understanding, then assign a worksheet where students apply proportional reasoning to predict field changes in new scenarios.