Hi guys, I'm constantly bothered by one assumption in my textbook..it says that the photon emitted by the accelerating electron boiled off from the cathode colliding into the anode, has E=hf neglecting the work function, since its negligible. I'm curious whether it's E=hf plus or minus the work function, and I'm really confused by this. Firstly, if I work backwards, like imagining it's a photon liberating the electron through the photoelectric effect instead, then the energy released should be E=hf + work function right? Since it emits the work function energy of the electron together with the photon right? However, how do we know they are separate values, since the work function energy can itself be incorporated into the hf value of the photon? Wouldn't it be the same then? Next, I think it's E=hf - the work function since if the accelerated electron has an initiall KE of E=eV=hf-work function then wouldn't the emitted photon have energy E=hf -phi too? Hmm but I think this whole second paragraph is invalid since the electron is initially boiled off by heating right? I'm not sure...I hope you guys can help me clear my confusion! Although the reason is not really needed, I'm curious to find out, thanks a lot!!