Blackbody Radiation: Thermal Spectrum and Temperature
draft readiness: experimental LightSpectra Both 12 min
Thermal-spectrum core is stable with Explore/Understand tabs; full launch-gate and parity signoff remain pending.
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Predict
Predict
If you heat an object up, does its peak emission shift toward redder or bluer wavelengths?
Play
Play
- Use the temperature slider (or presets) and watch the peak marker shift to shorter/longer wavelength.
- Toggle log vs linear intensity to see the long-wavelength tail more clearly.
- Use the visible-band highlight to connect spectrum shape to a qualitative color impression.
Explain
Explain
Use peak shift, curve shape, and T^4 scaling to explain what changes with temperature and what assumptions remain.
Learning goals
- Relate temperature to Planck-curve shape and Wien peak shift.
- Use Stefan-Boltzmann scaling to separate surface flux from total emitted power trends.
- Recognize that perceived color is an integrated visible-band impression, not only the peak wavelength.
Misconceptions targeted
- Peak wavelength alone determines observed color.
- Temperature alone determines luminosity for all stars.
- Red stars are hotter than blue stars.
Model notes
- The curve is generated from Planck's law and plotted in relative (normalized) intensity.
- Units: wavelength $\lambda$ is cm internally (displayed in nm); temperature $T$ is K.
- As temperature increases, the peak shifts to shorter wavelengths (Wien scaling: $\lambda_{\rm peak}\propto 1/T$).
- Surface emitted flux follows Stefan-Boltzmann scaling: $F = \sigma T^4$.
- Total luminosity additionally depends on radius, so temperature alone does not fully determine $L$.
- High-fidelity ZAMS/HR inference is handled in the separate `stars-zams-hr` instrument.
About this demo
Use the temperature slider (or presets) to compare where the spectrum peaks and how the overall power changes.