Lesson Plan

• Describe the Stefan‑Boltzmann law and identify each variable.
• Explain how radiative power changes when surface area is altered.
• Analyse the fourth‑power relationship between temperature and radiative power.
• Apply the law (including emissivity) to calculate power for given objects.
• Evaluate real‑world examples that illustrate the effect of emissivity.

• Projector and screen
• Whiteboard and markers
• Scientific calculators
• Worksheet with practice problems and a worked example
• Thermal‑imaging video or infrared camera demo
• Rulers/graph paper for sketching surfaces

Ask students why a black car becomes hotter than a white one on a sunny day. Review that all objects above absolute zero emit radiation and that they already know the concept of power. Explain that by the end of the lesson they will be able to predict how changes in temperature and area affect that power.

1. Do‑now (5'): Quick written response to “What everyday examples show objects emitting heat?”
2. Mini‑lecture (10'): Introduce the Stefan‑Boltzmann law, define emissivity, discuss area and temperature dependence.
3. Demonstration (8'): Show thermal‑imaging video of objects with different areas and temperatures.
4. Guided practice (12'): Work through the black‑plate example together, highlighting each substitution.
5. Independent practice (10'): Students complete worksheet problems involving area, temperature, and emissivity changes.
6. Check for understanding (5'): Exit‑ticket question – “If the temperature of a filament doubles, by what factor does its radiative power change?”

Recap the key relationships: P ∝ A and P ∝ T⁴, and the linear role of emissivity. Collect exit tickets to gauge understanding and assign a homework task to calculate radiative power for a household object using the law.