Lesson Plan

• Describe the relationship between electric field and electric potential for a point charge.
• Apply V = Q / (4π ε₀ r) to calculate electric potential given charge and distance.
• Analyse sign and unit conventions when using the formula.
• Solve typical A‑Level style problems involving point‑charge potentials.
• Identify common errors such as sign mistakes and incorrect unit conversion.

• Projector or interactive whiteboard
• Slide deck with derivation and example
• Worksheet with practice questions
• Scientific calculators
• Ruler/measure tape for demonstration
• Whiteboard and markers

Begin with a quick recall of the electric field concept and ask students to predict how the potential varies with distance from a charge. Highlight that today’s success criteria are to derive the potential formula, use it correctly, and spot common mistakes.

1. Do‑now (5') – Students answer a short slip‑sheet question on the link between E and V.
2. Mini‑lecture (10') – Derive V = Q/(4π ε₀ r) from the line‑integral of the field, emphasising sign and units.
3. Guided example (10') – Work through the +5 µC, r = 0.20 m problem; students fill steps on the worksheet.
4. Interactive practice (15') – Pairs solve three practice questions while the teacher checks for the listed pitfalls.
5. Concept check (5') – Quick poll/exit ticket: write the correct expression for potential and one common error to avoid.
6. Summary (5') – Recap the inverse‑distance law and its importance for upcoming topics on equipotential surfaces.

Summarise that the potential of a point charge follows an inverse‑distance relationship and that careful handling of sign and units is essential. For the exit ticket, students calculate the potential 0.10 m from a –2 µC charge. Homework: complete the additional worksheet problems and read the next section on electric potential energy.