Once you move past static electricity, and start thinking about how charges move, you move into the realm of ohm’s law. Before you get there though, there are a couple important things to think about. First is why charges move. When an object becomes charged, either positively or negatively, we say that it has some electrical potential. If you have two objects that have charges, one of two things can happen. Case one: both objects have exactly the same charge. In this situation, we say that they have exactly the same potential. Obviously, if we were to try to find the difference in potentials, you would get zero. Hypothetically, if both objects have a charge of (-1 charge unit), the difference between -1 and -1 is zero. Case two: the two objects have different charge, say -1 and -2. Here, if we were to find the difference, we would fine that there is a difference of 1 charge unit.
Now just having two objects with different charges in not enough to make the charge move. There needs to be one more thing. That thing is some path between the two charged objects. This path usually takes the form of a conductor, or wire, between the two charged objects. Once this conductor is in place, charge begins to flow. The charge will continue to flow as long as there is some difference in potential, and there is a path for the charge to move.
We’re not done yet. A potential difference is measured as voltage (V) with the unit of volts. The rate at which the current moves from one place to another is defined as the current (I), and that is measured in amperes. The final piece to this puzzle is the fact that even materials that do a good job at conducting electricity don’t do it with 100% efficiency. There is always some resistance to the flow of electricity. This is defined as resistance (R), and it is measured in ohms. The amount of resistance present in a material is a function of a bunch of things, like, the type of material itself, the temperature, the length of the conductor, and the thickness of the conductor.
These three pieces come together and are related by Ohm’s Law. Ohm’s Law simply states that V = I * R, or, voltage = current * resistance.

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