| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand how the concept of electric potential leads to the electric potential energy of two point charges and use EP = Qq / (4πε0 r) |
Learning Objective/s:
- Describe the relationship between electric potential, electric potential energy, and charge.
- Explain how the formula U = Qq / (4π ε₀ r) is derived from V = Q / (4π ε₀ r) and U = qV.
- Apply the formula to calculate the potential energy of two point charges, including sign considerations.
- Analyse common sign conventions and identify errors in calculations.
- Solve practice problems involving changes in potential energy.
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Materials Needed:
- Projector or interactive whiteboard
- PowerPoint slides or digital presentation on electric potential
- Worksheet with worked example and practice questions
- Scientific calculator
- Whiteboard and markers
- Optional: PhET simulation “Charges and Fields”
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Introduction:
Begin with a quick demonstration: bring two charged balloons close together and ask students what they feel. Recall that electric potential describes energy per unit charge, a concept they met when studying electric fields. Today’s success criteria: students will be able to derive and use the potential energy formula for two point charges and correctly interpret sign conventions.
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Lesson Structure:
- Do‑now (5′) – Mini‑quiz on the difference between V and U displayed on the board.
- Mini‑lecture (10′) – Review definitions of electric potential, potential energy, and derive U = Qq / (4π ε₀ r) using U = qV.
- Guided example (12′) – Walk through the worked example (Q = +5 μC, q = –2 μC, r = 0.10 m), emphasizing unit conversion and sign.
- Interactive simulation (8′) – Use PhET “Charges and Fields” to manipulate two point charges, observe changes in V and U, and record observations.
- Practice problems (10′) – Students complete three practice questions in pairs while the teacher checks reasoning.
- Check for understanding (5′) – Exit ticket: write the formula for U and state what a negative value indicates.
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Conclusion:
Summarise that electric potential energy depends on both charge magnitudes and separation, with the sign reflecting attractive or repulsive interactions. Collect the exit‑ticket responses to confirm understanding. Assign homework: a worksheet with additional charge‑separation problems and a short reflection on the physical meaning of negative potential energy.
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