How is AC current transmitted through power lines if it changes direction regularly after a half-cycle proportionally in the opposite direction?

Question

How does the current flow in one direction if the electrons are hoping back and forth? Shouldn’t the net current be zero?

In: 3

Answer 1

Imagine a really long belt running along the pylons instead of electrical wires. This belt could run continuously forwards, and people could extract useful power by having the belt rotate a wheel which is then linked to their machinery.

Or the belt could reciprocate backwards and forwards. There is no net motion of the belt, but we can still extract useful power. The belt would be attached to a connecting rod, which would move backwards and forwards and so rotate a crank, just like in any reciprocating engine. This crank would be attached to a shaft which would rotate forwards continuously and be attached to the machinery, just as in the example above.

We have motors that can make use of electrical fields that oscillate backwards and forwards and turn that into continuous motion to do useful stuff. In fact Alternating Current (AC) motors have historically been easier/better to make (modern motors are likely to be AC, but variable frequency).