blackbody and blackbody radiation

Idealised perfect absorber (and emitter) of radiation, whose emission depends only on its temperature.

Spectral radiance (Planck’s law):

$$B_{\lambda }(T)=\frac{2h{c}^2}{{\lambda }^5}\frac{1}{e^{hc/\lambda k_{B}T}-1}$$

where:

• $B_{\lambda }$: spectral radiance (W m⁻² sr⁻¹ m⁻¹),
• $\lambda$: wavelength,
• $T$: temperature (K),
• $h$: Planck constant,
• $c$: speed of light,
• $k_B$: Boltzmann constant.

Peak wavelength (Wien’s displacement law), with $b\approx 2.898\times 10^{-3}$ m K:

$${\lambda }_{\max }=\frac{b}{T}$$

Integrated over all wavelengths and directions: Stefan-Boltzmann law.