Question

why potential isnt zero at centre of ring

Answer 1

lectrical potential by itself is not a measure how much a charge wants to go along the field lines. You can have a point with very high potential and electric field zero, if the neighboring points have the same potential. The electrical potential is only is a measure of the energy you need to move a positive charge from a point of zero potential to the point of this given electrical potential. For the local force on a charge, corresponding to the electric field, the negative gradient of the potential at that location is essential. Therefore, you can have a location with zero potential where you have a nonzero electric field. In addition the electrical potential is not unique. You can chose the zero arbitrarily.

Answer 2

Hope helps you

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