The B-battery attracts electrons to the plate and so reduces the crowd in the tube.
The B-battery will want to take in electrons at its positive terminal and to send them out at its negative terminal.
Of course, at that same instant an equal number leave the other plate and start off toward the B-battery and the filament.
This new battery we shall call the “plate battery” or the “B-battery.”
Of course, if we make the grid positive we move the clip so as to use fewer cells of the B-battery.
