PhET Simulation: Charges and Fields. Part 1. The electric potential (voltage) at a specific location is equal to the potential energy per unit charge a charged object would have if it were at that location. If the zero point of the voltage is at infinity, the numerical value of the voltage is equal to the numerical value of work done to bring in a unit charge from infinity to that location. Select Show numbers and grid in the green menu, and drag one positive charge to the middle of the screen, right on top of two intersecting bold grid lines. Using the voltage meter, you should find that 1m away from the charge, the voltage is 9 V. 1) What is the voltage 2 m away from the charge? ANSWER: 2) What is the voltage 3 m away from the charge? ANSWER: Part 2. Another way to study voltage and its relationship to electric field is by producing equipotential lines. Just like every point on a contour line has the same elevation in a topographical map, every point on an equipotential line has the same voltage. Click plot on the voltage tool to produce an equipotential line. Produce many equipotential