Hello everyone! Let me first say how cool it is that this forum exists, I wish I'd thought of coming here years ago. I am trying to understand how EM radiation works. From the high school physics that I've learned I have been under the impression that reflection was due to electrical absorption. Furthermore the physics that I've read have implied that light will enter and exit a material with the same frequency. So my question is, when the atoms increase in kinetic energy due to exposure to light, what happens to the energy of the light? My idea is that the frequency should degenerate proportionally to the increase in thermal radiation from the body that is associated with the increase in temperature. As I indicated before I am also confused as to whether matter only interacts with certain frequencies of EMR. Would a beam of light at a wavelength that does not excite a certain material make any change in the material's thermal energy? Edit: And just after posting I of course stumble upon http://en.wikipedia.org/wiki/Raman_spectroscopy" [Broken]. Typical. I will continue studying from there, but I would still appreciate any thoughts on this general subject.