2

Planck and other
Formulae

•Planck formula gives intensity of light at each
wavelength

–It is
complicated. We’ll use __two simpler__ formulae which can be derived from it.

•__Wien’s law__ tells us
what wavelength has maximum
intensity

•__Stefan-Boltzmann law__ tells us
total radiated energy per unit
area

From our text: Horizons, by Seeds