Ok, I've been reading up on the EM field and how it exerts force on charged particles. By exerting this force it creates 'ripples' in the EM field and this is felt by other charged particles as a force (either of attraction or repulsion). We say that the two particles exchanged a virtual photon because QFT tells us that the quantised excitations of a field are its associated particles. My question is how does this image of the EM field work when explaining the emission of photons from electrons. Even as simple as heating an iron rod: the electrons in outer shells of the iron atoms becomes excited by absorbing energy from the heat source, and then emit photons to fall down back to their ground energy state. How does the heat source transfer energy to the electrons? Why doesn't it stay as kinetic energy on an atomic or even molecular scale? How do the electrons emit photons when they are clearly not interacting with any other charged particles in the process? Thanks in advance, I know it's quite a lot!