The current is transported from place to place through wires. The flow of the current through these wires is very much like the flow of water through pipes. The pressure behind the water causing it to flow along the pipe corresponds to the voltage in the current. The voltage is what makes the current flow through the wire between two points and the current will flow only when one of these points has a lower voltage than the other. To send the current a certain distance a certain voltage must be used.
Higher Voltage Increases Power.
In the pipe there is a resistance to the flow of water. This resistance is furnished by the walls of the pipe. In the same way there is a resistance to the flow of the current through the wires. The voltage must always be strong enough to overcome this resistance or else the current will not flow. If the pressure behind the water in the pipe is not strong enough to overcome the resistance of the pipe walls, then when we turn the faucet no water will flow. When we turn the switch no current will flow under the same condition.
When Edison first operated his electric service lines in New York city he used 110 volts and then 220 volts to send the current over comparatively short distances. At the present time on certain long-distance lines in southern California the voltage behind the current is 220,000 volts. 