Wiens Law

  • Most objects emit radiation at many wavelengths

  • However, there is one wavelength where an object emits the largest amount of radiation

  • This wavelength is found with Wiens Law:

lmax = 2897 mm / T(K)

Q: At what wavelength does the sun emit most of its radiation?   ANSWER

Q: At what wavelength does the earth emit most of its radiation?  ANSWER


Suppose your surface body temperature averages 90F. How much radiant energy in W m-2 would be emitted from your body? What is the total radiant energy emitted by your body in Watts? At what wavelength is this radiant energy emitted?