How does the charge ever move forward in AC if electric charge moves forward then backward then forward then backward over and over again?

Answer 1

It is not the charge moving. What really happens is that from a certain point the potential difference increases sine-wave shaped to its positive maximum, decreases to zero, then inverts and increases to its negative maximum in order to decrease to zero again. This goes on and on... Imagine a conventional electric lamp, consisting of a tungsten wire in a glass bulb, being connected to this alternating voltage. At increasing potential difference the current through the wire increases as well, generating enough heat to make the wire glow. In most European countries a complete cycle takes 1/50 second. This means that our lamp flickers 100 times per second (50 times positive and 50 times negative). Because this happens so fast, the wire doesn't get the time to fully cool down. We don't see any flickering as our eyes are much too slow. Alternating current is generated by the power works automatically, as the generator is nothing else than a big dynamo, which basically is an electric coil being rotated through a magnetic field. This rotation through the field lines causes the fluctuating (or alternating) current. Alternating current is required to make mains Transformers work, in order to transform dangerous voltages to safe levels.