Example - the potential from a point charge is:
We usually define V = 0 at infinity.
The simulation shows the equipotentials for a non-uniform field, specifically the field from a point charge. In which direction is the field?
The equipotentials get closer together near the center. What does this tell you about the electric field as you get closer to the center?
Let's say a +q test charge is moved horizontally a distance r. What is the change in potential experienced by this charge? Assume the charge in the center is a -Q charge.