Planck's distribution

 

T=800; % (K)

Eblk(T) % backbody hemispherical power (W/m^2)

ans = 2.3226e+04

 

lMax(T) % wavelength at peak in blackbody spectral distribution

ans = 3.6223

 

Eblkl(lMax(T),T) % backbody spectral hemispherical power at peak (W/m^2/um)

ans = 4216.4

 

FlT(lMax(T)*T) % fraction of spectral distribution with wavelengths shorter than peak

ans = 0.25007

 

l=logspace(0,2,100); % create wavelength span

loglog(l,Eblkl(l,[400 800])); % plot Planck's distribution for 400 and 800 K

axis([1 100 1e-2 1e4])