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:

l_max = 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

QUESTION FOR THOUGHT:

Suppose your surface body temperature averages 90°F. 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?