I mean to say for a hollow sphere, can its electric potential be zero at its centre and can electric field intensity be? And if they are zero then what physical meaning does it gives? Since, these quantities can't be seen or touched, I don't exactly know what's going? So please can you explain in short in a simple language and with some useful equations Note:-Analogies such as Water bucket-Capacitor etc will be appreciated. Thanks!
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Electric potential (energy per charge) is analogous to water pressure.
What makes a water particle move is not the pressure in itself, though. It is the pressure difference. A particle will only move if it is being pushed from more one side than from the other. If pushed equally from both sides, it doesn't move. Particles inside a pressure container don't move, but if the tab opens, then they all flow towards this place of lower pressure.
Electric potential does the same for a charge. Charge move towards points of lowest energy. Having the same energy level or potential at every point (connecting both ends of a wire to the same battery pole, e.g.) makes no charge move. But having a charge difference (connecting the one end to the positive pole (at high potential) and the other end to the negative pole (at low potential), makes them move towards the point at lower potential.
About the hollow sphere, you can imagine a circular pipe e.g. The pressure is the same all around this pipe, so no particles move around. Just like the charge do not move around on an equipotential surface. In the centre of this pipe-ring there is much lower pressure - but also no access. The water particles are pressed towards the wall but then stop because the wall is strong enough to balance out this pressure. On a conducting sphere, the same happens because the sphere is a conductor but the air inside it not - the charges meet "a wall" when trying to escape from the conductor. The air is simply preventing charge to move inside it with enough force to balance out the electric force that pushes the charges towards the conductor edge.
If the potential is suddenly very high, then the air might "break down". This is called breakdown voltage and is what happens in lightning storms when otherwise insulating air suddenly becomes conducting. This is equivalent to the pipe wall breaking from the pressure being too high.
