I was just reading R.Feynman's Lectures on physics Vol I and I came across this discussion in which he says that magnetic field results from an electric field i.e relative motion of electrons and so on. Further, he says that the electomagnetic spectrum consists of light waves.... The whole spectrum is brought about by the oscillations of electrons. i.e the frequency of oscillations determine the various effects such as x-rays, microwaves, light itself... What's puzzling me now is that from where do the electrons gain energy for sustained oscillations at the "light frequency" (5x10^14-5x10^15) so that we can actually "see"???