1. Static Electricity, or The Wax and The Wool
Let’s bring the concepts of voltage and current together at this point in a simple example. If you take a piece of wax and rub it with some wool cloth, you are transferring electrons from the wool to the wax. The wax will end up with a surplus of electrons, and so the wax is negatively charged. The wool, having lost the electrons, will have a more positive charge. So now there is an imbalance of charge between the two objects, and they want to return to their state of equilibrium, with the correct number of electrons. So they pull on each other, they are attracted. But although they are attracted, there is nothing the electrons can do to cross the gap; they are helpless and destined to forever remain imbalanced. Unless, we can add a conductor between the two objects in the form of a small wire. The conductor provides a path for the electrons to travel along between the two objects, which they will immediately due in order to restore the balance of charge by flowing to the electron deficient wool cloth. Shortly, the charges will have neutralized and the flow of electrons will cease. Wax and wool are satisfied again.
So we can see that by rubbing the two objects together, we created an electric field between them: two charges attracted to each other. There is a certain amount of potential energy that is stored as well, in the imbalance created by the electrons. This potential energy is the voltage, the force that made the electrons flow between the wire back to their respective conditions. And that electron flow in the conductor is current. Remember that the actual electrons flowing in the wire are from the wire itself; the charged objects have provided the force to move them.
So at this point, hopefully your understanding of current and voltage has been improved even if it’s just a little. Of course, there is plenty more to be learned about each topic above, but the basics are there and hopefully the foundations for extended learning are there too. If I am to stumble through the majority of the concepts introduced in a mechanical engineering degree, with a poor analogy here and a poorer analogy there, we’ll have to leave the discussion of current and voltage here for now.
the first year engineer 