Why is the end of the hot filament where negatively charged electrons are being fired called the cathode end. 'cat' in chemistry means positive, I assume the same goes in physics as well?
That doesn't make any sense either. An electron will move from a low electrostatic potential to a high potential. It has nothing to do with something being negative or positive. I could have the electrons coming out of a conductor at -10 V and it will still be "attracted" to a conductor at - 5 V, because that latter conductor is at a higher potential. The difference in the potential will create a potential gradient, thus, electric field.So that is the main reason. The receiving end is receiving the electrons hence will be made more negative so that end is called the anode.