← Back to Labs

Blackbody Radiation – Planck's Law

3000 K
Temperature 1
967 nm
Peak λ (Wien)
0
Total Power (W/m²)
▓▓▓
Emitted Color
3000 K
6000 K
12000 K

Planck's Radiation Law (1900)

Planck resolved the "ultraviolet catastrophe" by quantizing energy. The spectral radiance is:

B(λ,T) = (2hc²/λ⁵) × 1/(exp(hc/λkT) − 1)
Wien's displacement law: λ_max × T = 2.898 × 10⁻³ m·K
Stefan-Boltzmann law: P = σT⁴ (σ = 5.67×10⁻⁸ W/m²/K⁴)

The Rayleigh-Jeans classical prediction (B ~ λ⁻⁴T) diverges in the UV. Planck's quantization fixes this. The Sun (5778 K) peaks at ~502 nm (green), but integrated emission appears white/yellowish. The cosmic microwave background (2.725 K) peaks at ~1.1 mm.