Is accelerating charges the only way to produce EM radiation?
What about gamma radiation emitted from the nucleus of an atom? Does that count as accelerating charges? How?
Are there other ways of producing EM radiation? Or are these the only two ways?
What about collision of particles? What about emission of a photon as an electron falls to a lower n state?
Would this be a correct way to describe it (noting this is for introductory level, so a grasp of the basics would be handy without confusing with the specifics):
All forms of EM radiation are produced by accelerating charged particles. The only exception is gamma radiation, which is produced from the nucleus of radioactive atoms.
However, note that some physicists would argue that gamma radiation released from the nucleus of atoms also involves accelerating charged particles (in this case, protons within the nucleus).
Also note that it is theoretically possible to accelerate charged particles sufficiently that they would cause EM radiation at gamma-ray frequencies. Many believe this is the mechanism that causes gamma-ray bursts.
However strictly speaking gamma-ray-frequency EM radiation caused by such a mechanism would be more correctly called 'high frequency X-ray radiation', while 'gamma-rays' come from the nucleus of an atom.