The current in an ac power line changes direction 120 times per second, and its average value is zero. Explain how it is possible for power to be transmitted in such a system.

Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction.

Alternating current (AC) is the type of electriccurrent generated by the vast majority of power plants and used by most power distribution systems. Alternating current is cheaper to generate and has fewer energy losses than direct current when transmitting electricity over long distances.

The electrons in the conducting wire are vibrating through the wire when ac power is given to electrons, they vibrate, move forward and back such that energy is transferred from one electron to other. It like the toy calledNewton’s Cradle, when ball strikes a group of static balls, the energy transfer through the balls to the final ball and it starts to move. This is how energy is transferred to other side in ac power supply.