| Lesson Plan |
| Grade: |
Date: 01/12/2025 |
| Subject: Physics |
| Lesson Topic: use the Stefan–Boltzmann law L = 4πσr 2 T |
Learning Objective/s:
- Describe the Stefan–Boltzmann law and its variables.
- Apply the rearranged formula to calculate stellar radii from given luminosities and temperatures.
- Convert astronomical units to SI units and interpret the physical meaning of the results.
- Identify common errors (unit mismatches, missing T⁴ term, omitted square‑root) and correct them.
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Materials Needed:
- Projector and screen
- PowerPoint slides with formula derivation and example
- Worksheet containing practice stars (luminosity & temperature)
- Scientific calculators (or calculator app)
- Printed Hertzsprung‑Russell diagram handout
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Introduction:
Begin with a striking image of a red supergiant and ask students how we know its size without measuring it directly. Recall the previous lesson on black‑body radiation and introduce the success criteria: students will be able to compute a star’s radius using the Stefan–Boltzmann law.
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Lesson Structure:
- Do‑Now (5'): Quick mental‑check – write the Stefan–Boltzmann equation and list its constants.
- Mini‑lecture (10'): Derive the radius formula, emphasize the T⁴ term and unit conversion.
- Guided practice (15'): Walk through the Sun example on the board, students follow on worksheets.
- Independent practice (15'): Students calculate radii for three different stars from the table, using calculators.
- Peer review (5'): Exchange worksheets, check each other's calculations against a solution key.
- Concept check (5'): Whole‑class quiz using clickers – identify the most common pitfall in a given calculation.
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Conclusion:
Summarise how luminosity, temperature, and radius are linked and why accurate unit handling is crucial. Students complete an exit ticket: state one real‑world implication of knowing a star’s radius. Assign homework to research a star of their choice and compute its radius using the law.
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