Electrical – Why can’t an object have “absolute” zero potential


I've read a lot of questions about this on this site and others, and every answer seems to believe that there can't be an object with zero potential/voltage, unless you take it at infinity, which seems pointless, or arbitrarily define it as zero.

From my understanding, potential difference is proportional to q/r, so I can see why, if you just look at r, it's difficult to have zero potential.

But what if we look at q? Surely, if an object has a net charge of zero, then you must be able to say it has zero potential.

Best Answer

Electric potential between two points is defined by: $$V = -\int \mathbf{E} \cdot d\mathbf{l}$$ Where the integral is taken over a curve that connect the two points you are taking the potential across.

It is apparent that if you select any potential at point A, you can pick an electric field that will give you a lower potential at point B. Therefore, there cannot be a minimal potential i.e. the potential is not bounded below.