al physics electric field

Questions:what is the potential difference between sphere A and B?

The potential differences between A and B in case 1 and case 2 are the same.
Since potential difference V = E.d
where E is the electirc field between A and B, and d is the separation between A and B
But E depends on the chrages on A and B, which are the same in both cases, and d is also the same in both cases, thus the potential differences V are the same.
[Note: the application of the equation V = E.d is only approximate for the sphere configuartion, as E is not uniform. It is only used as a simple illustration of the phenomenon]
what is the potential of sphere A and B in both cases?
Case 1: potnetial of A is +ve, potential of B is zero (earthted)
Case 2: potnetial of A is +ve, potential of B is -ve
The potential of A is case 1 is higher than that in case 2 in order to maintain the same potential difference between the two cases.
if i replace the metal spheres with parallel plates,are there any difference
The above results still hold except that the values of potential would be different.