if we have 2 parallel plates for which one is at positive 2.0 kV and the other at positive 6.0kV, I wanted to know, what does it mean for those two voltages being positive ? and how is voltage of those plates even increased ? what happens inside the material and what is this voltage that it receives? in the form of what ?
This means the voltage with the ground is positive. Than both of the plate becomes positive. Electrons from the plates goes to the ground and its makes both plate positive. But if the plates are disconnected from the potential it can not able to bound more charge as like a capacitor. Because in a capacitor charge are bounds due to the attraction of positive and negative charge. But if both plates are positive they try to repeal charge or try to neutralise. Again with increasing the positive potential of the plates by withdrawing electrons. But since the opposite plates also positive , opposite plates will attract the electrons and try to resist the increase of potential.