Glowing Hot

The colours of hot things

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Stefan–Boltzmann: power $\propto T^4$; Wien: $\lambda_{\text{peak}} = 2.9 \times 10^{-3}/T$.
• The Sun’s 5,800 K surface peaks in visible light; people peak near 10 µm.
• Hot objects go from red to white as they heat up.

Steps

1. Blackbody radiation
2. Match the Sun
3. Your infrared glow
4. Twice as hot
5. A filament’s peak
6. Red hot, white hot