Blackbody radiation and Wien’s law

Theory

Every hot body emits a continuous spectrum given by Planck’s law. Wien’s displacement law gives the peak: ${\lambda }_{max}=b/T$ with $b\approx 2.898\times 10^{-3}$ m·K. The total power grows as $\sigma T^4$ (Stefan–Boltzmann).

What to observe

• The Sun (5800 K) peaks near 500 nm, in the visible.
• Doubling T multiplies the emitted power by 16.

Try this

• Raise T₁ to 10 000 K: the colour turns bluish.
• Lower it to 2700 K: most energy becomes infrared.

Also available in: Radiação de corpo negro e lei de Wien (Português) · Radiación de cuerpo negro y ley de Wien (Español)