| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Know that for an object to be at a constant temperature it needs to transfer energy away from the object at the same rate that it receives energy |
Learning Objective/s:
- Describe radiation as energy transfer by electromagnetic waves and its dependence on temperature, surface area and emissivity.
- Explain the energy‑balance condition (incoming power = outgoing power) for an object at constant temperature.
- Apply the Stefan‑Boltzmann law to calculate the radiated power of a surface.
- Solve equilibrium‑temperature problems involving radiation and identify common misconceptions.
|
Materials Needed:
- Projector and screen
- Calculator or computer with spreadsheet
- Worksheet with example problem and practice questions
- Thermometer or infrared temperature sensor for a brief demo
- Black matte sphere model (or image) to illustrate emissivity
- Whiteboard and markers
|
Introduction:
Begin with a quick question: “Why does a warm cup of tea eventually cool down even though it is still receiving heat from the room?” Connect this to students’ prior knowledge of heat transfer modes. State that today they will discover how radiation can balance energy flow so an object stays at a constant temperature, and they will be able to predict equilibrium temperatures using the Stefan‑Boltzmann law.
|
Lesson Structure:
- Do‑now (5'): Students answer the opening question on the board and share ideas.
- Mini‑lecture (10'): Define radiation, present key concepts and the energy‑balance equation.
- Derivation & discussion (10'): Introduce the Stefan‑Boltzmann law, explain each term and its physical meaning.
- Guided example (15'): Work through the black sphere problem step‑by‑step, calculating surface area, power in, and equilibrium temperature.
- Student practice (15'): Pairs solve a similar problem on the worksheet, with teacher circulating for support.
- Misconception check (5'): Quick poll using true/false statements about common errors.
- Exit ticket (5'): Write one sentence summarising why an object can have zero temperature change despite ongoing energy flow.
|
Conclusion:
Recap that constant temperature requires equal rates of energy gain and loss, and that the Stefan‑Boltzmann law quantifies radiative loss. Collect exit tickets to gauge understanding, and assign homework: complete two additional radiation‑balance problems from the textbook. Remind students to bring their calculators for the next lesson on convection and conduction.
|