does V=Ed apply only to parallel plates?

Question

Does the equation V=Ed apply only to parallel plates, or can it be used for charged suspended objects as well.

Answer 1

Ths equation is applicable to anything, not just parallel plates. The only caveat is that the electric field, E, must be uniform over space and constant through time.

Answer 2

It only applies if the field is uniform over the distance d. It is more accurate to say that ∆V = E*∆d for values of ∆d such that E can be considered constant.