Blackbody Radiation: free physics simulation
Heat an object from body temperature to a blue star and watch its colour and spectrum change.
▶ Open the simulationFree, no sign-up. Works on phones, tablets and laptops.
The science
Every object gives out electromagnetic radiation because of its temperature. A hotter object gives out much more energy (proportional to T⁴) and its peak moves to shorter wavelengths (Wien’s law). That is why a stove ring glows red, a bulb filament yellow-white and the hottest stars blue. Planck’s explanation of this curve in 1900 started quantum physics.
λpeak = 2.898 × 10⁶ / T nm, P ∝ T⁴
Things to try
- Heat it to about 1,000 K and watch it start to glow red.
- Match the Sun by putting the peak near 500 nm.
- Save a curve, double the temperature and compare.
Topics covered
thermal radiation temperature wien stefan boltzmann planck star colour infrared spectrum quantum
How to use it
Open the simulation, then change the experiment live with the sliders, checkboxes and buttons in the side panel. Drag objects on screen where it makes sense, and use Pause, Step, Speed and Reset in the bottom bar to study every moment.
Frequently asked questions
What does the Blackbody Radiation simulation show?
Every object gives out electromagnetic radiation because of its temperature. A hotter object gives out much more energy (proportional to T⁴) and its peak moves to shorter wavelengths (Wien’s law). That is why a stove ring glows red, a bulb filament yellow-white and the hottest stars blue. Planck’s explanation of this curve in 1900 started quantum physics.
What is the key equation?
λpeak = 2.898 × 10⁶ / T nm, P ∝ T⁴
Is the Blackbody Radiation simulation free?
Yes. It runs free in any web browser on phones, tablets and laptops, with no sign-up or download.
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