<p>Origin: You've basically come to the correct conclusions. Way to go!</p><p>I'll elaborate a bit though, because I like to hear myself talk.</p><p> </p><p>A free proton or electron...lets simplify that to a "free charge" can absorb any photon, as you said a "continuum" of photons. The only difference is in how the charge reacts, as momentum and energy of the photon are conserved. So the charge gets a kick in the direction the photon was going, and the size of the kick is proportional to the energy of the photon. </p><p>Also a free charge that accelerates, due to say a magnetic field or a collission, EMITS a photon, once again proportional to the acceleration (energy change) of the charge. This does mean protons from a nuclear reaction will shed photons in the cooling water. Though there is another, seperate, effect called Kerenkov radiation that comes into play in such scenarios due to the extreme high speed (relativistic) of such photons. </p><p>When an electron is in an atom, it is "bound" and only has specific 'quantized' energies it can absorb. Anything else passes it by. This is the key fact behind emission and absorption spectra, a fundamental tool in astronomy. It also has more mundane consequences. For instance it's why glass is clear! The electrons in the atoms of glass are in energy states that do NOT allow them to absorb visible photons, and so they are transparent to us.</p><p> </p> <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>