it will always be slightly hotter on the side where there are more electrons waiting to pass through, so we sometimes see a slightly different burn pattern on the screen. please note this does not impact performance as regardless where and how the heat is being produced on the screen, it has very little differentiating effect on the vapor being produced.
Now if we were to reverse the polarity, the positive electron's traffic jam starts on the other side of the screen, so the hot spots which leaves the burn pattern/carbon spotting behind gets reversed, or what appears to be "evened out" afterwards. does that make sense?
Yes, but while it might make sense to some of us, it doesn't to the electrons. And it's what they think and do that matters.
Current is the more or less orderly flow in one direction. In reality, the 'free electrons flow randomly around atom to atom (or they wouldn't conduct), much like individual water molecules in a pipe. Put some pressure on that water (voltage is electrical pressure) and you get a net flow in one direction who's magnitude is set by the pressure (voltage) and opposition to flow (resistance) and some 'magic factor' to do with water that relates those two to flow rates (Ohm's Law in our case).
As in the water pipe analogy there's no difference between those entering one point or leaving another really, an electron goes into the wire on one end and a different one comes out the other. But it's one for one and they are interchangeable. A light bulb filament is heated the same in either direction, the heating happens atom by atom.
This is not true when you cheat conduction like in a vacuum tube where the electrons leave metal conductors and venture into free space. Lighting is similar. Here the mass of the electrons (tiny as it is) combines with the square of their speed such that the power (heat) is developed on impact not in the free flight. The positive plate (anode) glows where the beam hits. But that's not us......at least as I understand it. Weld heat works this way. As do say carbon arc electrodes.
Bad wiring burns out where the weak connection is without regard to which way it flows.
As an interesting point, we had it wrong from the start. Current is actually defined as plus to minus, go look it up.
Conventional Current (the way we believed it to happen initially) is not the same as
Electron Flow (what we now know to be true). Text books are written 'both ways', the instructor picks. The arrows and such go the other way in the other book. I learned Conventional Current (so called because it was the convention.....) even though we knew it was 'backwards' (it doesn't matter, of course, really) but taught Electron Flow later on. From time to time I'd screw up and slip back.....the more blank than normal look on the student's face was always a good clue there.... Same Ohm's Law. Same heat.
When I went to school initially it was easy 'current goes from top to bottom and signal from left to right' was the rule for schematic circuit drawings. Not so any more.
I joke about electrons going uphill and all, but that's not how it works. Resistance causes friction (superconductors, no resistance, don't heat) at the local level. Think if it as a room full of people. Push one in one door, and another (different) one leaves by another door. Inside the room, people still mill about randomly, but 'the average guy' moves a little bit toward the out door?
OF
A better example might be in arc welding. Positive goes to rod for a larger bead (hotter side). I read they reverse the polarity for a lesser bead. AC is in between. Found some info on this here in a different forum.
