In regards to voltage and electrical potential, I have a question. I understand the voltage to be the difference in electrical potential of two separate points. So in an analogy am I correct to compare this to a bowling ball being 4 feet off the ground. So the bowling ball has a gravitational potential at 4 feet, and a gravitational potential at zero feet (the ground). Now my question is, is a single point of electrical potential useful at all without a second point for reference? For example, if the electrical potential at one point is 200 J/C, then does that mean anything without a point of reference to the 200 J/C? The same as the bowling ball would have no meaning without reference to the ground? So does a single point tell us anything about how a charge will behave at a point, or do you need the difference between points to tell how it will behave. I am thinking you need both points, because a bowling ball 4 feet high essentially can't "mean" 4 feet high without a reference point to 0 feet. So how can electrical potential at one point even be measured without having a reference to something else. That is how can V = kq/r be an equation that tells anything when it doesn't have a reference point. What does "electric potential" a single point refer too (not voltage the difference between two points)?