Lesson Plan

• Describe the relationship between electric field, force, and charge.
• Apply Coulomb’s law to calculate the magnitude and direction of the force between point charges.
• Derive the expression for a uniform electric field between parallel plates from surface charge density.
• Solve problems involving electric field strength, potential difference, and the force on a charge.

• Projector or interactive whiteboard
• Slide deck with formulas and diagrams
• Worksheet with practice problems
• Scientific calculator (or app)
• Ruler/graph paper for sketching field lines
• PhET electric field simulation (optional)

Begin with a quick demonstration of two oppositely charged balloons attracting, prompting students to recall how charges interact. Review the definition of electric field as force per unit charge and state the success criteria: students will correctly use Coulomb’s law and relate it to uniform fields.

1. Do‑now (5'): Solve a recall question on the definition of electric field.
2. Mini‑lecture (10'): Derive Coulomb’s law, discuss the constant ε₀, and link to force on a charge.
3. Worked example (10'): Walk through the sample problem of two point charges, emphasizing unit conversion and direction.
4. Interactive simulation (8'): Use the PhET electric‑field applet to visualise forces between charges and the uniform field between plates.
5. Guided practice (12'): Students complete worksheet problems on force calculations and field between parallel plates while the teacher circulates.
6. Exit ticket (5'): Write one sentence explaining how Coulomb’s law leads to the expression for a uniform field between parallel plates.

Recap that Coulomb’s law provides the fundamental link between charge and force, and that a large charged plate creates an approximately uniform field that can be expressed using surface charge density. Students submit their exit tickets and are assigned homework to calculate forces for additional charge configurations.