Problem: An electron moving parallel to the x-axis has an initial speed of V1 at the origin. It's speed is reduced to V2 at the point x=2 (V2<V1). Calculate the potential difference between the origin and the point x=2. Which point is at the higher potential? I was able to calculate the potential difference pretty easily but I got the second part wrong. I thought the higher potential would be at the point x=2 but the book says the origin. Here is my reasoning, please tell me where I'm going wrong: Since the electron is decelerating along the positive x-axis, it is experiencing a force due to an electric field pointing in the -x direction. Since electric potential decreases as you move along the direction of an electric field, the origin should be at lower potential. Thanks.