In DC, we have learnt that the electrons move from their position through the conductor, resulting in a current. They leave their positions on the application of a potential difference, and move or flow in the direction of higher to lower potential, thereby causing a current. But what about AC? Say the frequency is 50Hz. What is altering in AC? It is said that the sine graph of AC is positive for 50 times and negative for 50 times in a second. It is also said that the direction of AC keeps changing. Does this mean that the live will become the neutral in our house wires? But that doesn't happen. Then what is the thing that changes direction 50 times a second? Is their actually any flow of electrons in AC, or the electrons just vibrate about their mean positions, resulting in a current? If so, how can a current result from harmonic vibrations of electrons?