Answer
In a uniform electric field, electric potential increases or decreases in a linear fashion for movement in a line.
If the electric potential V is constant in some region, then the electric field in that region is zero.
Work Step by Step
If the electric field in a region is uniform, then the electric potential V is increasing (or decreasing) linearly when one moves in a straight line. For example, if the electric field is 10 V/m in the positive x-direction, then if you move in the positive x-direction, the electric potential drops by 10 V for every meter that you move.
