the flow of electricity through wire and cable from the main upply can be compared with the flow of water through pipe from a water tank.
when the tap i turned off, the water doe not move, but when a tap i turned on the height of the water in the tank exert preure on the water in the pipe and force it through the outlet. thi water preure i comparable with voltage in electricity. the rate of the water flow, imilar to the flow of current, i controlled by two thing: the preure and the ize of the outlet. for example, a very narrow pray allow le wager to flow than a wide pipe. imilarly in electricity, a very thin wire retrict or reit the flow of current.
electrician meaure thi reitance in ohm and the flow of the current in ampere