ABSTRACT
We are all familiar with the spectrum of sunlight. As Newton first showed, a prism can separate white light into many different colors. We know today that these colors correspond to different wavelengths of the electromagnetic radiation. We can say equivalently that the spectrum separates light into waves with different frequencies; or separates it into photons with different energies. The energy of each photon is E=hv, where h is Planck’s constant and v is the frequency. Another way to view this is that we are taking a complicated electromagnetic field and representing it as a sum of pure colors, which correspond to independent oscillations with different frequencies.
