So in England we have the ground prong so our cables are all the same, however I know in the states and other places they don’t, so how come no damage is caused if the positive and negative are the wrong way around?
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It’s *alternating current*; both prongs alternate “positive” and “negative” dozens of times every second. And yet still, because one of them might be “chassis/earth ground” (still more positive than the negative and more negative than the positive, dozens of times every second), most plugs (and jacks) in America have one prong slightly larger than the other so they can’t get “plugged in the wrong way”.
The easiest way to visualize it is to think of water. DC electricity, like you’d get from a battery is like a steam of water. The charges flow in one direction.
AC electricity that you’d get from the outlet works differently. The water moves forward, then moves back again. The charges are pushed from one prong, through the appliance, to the other prong. Then the flow reverses. This reversal happens 50/60 times a second (50/60 Hz).
So each prong on the plug accepts charge coming into it and charge being pushed out of it. Therefore, you can plug it in either way, and it’ll be fine.
For some devices, it doesn’t matter. For others, it’s does and those plugs will either have one larger prong, a ground prong, or both.
Outlets in the US definitely have a ground prong in the outlet and a larger side vs a smaller side and have since like the 70s. Only old houses/outlets in the US have 2.
It’s AC. What positive and negative? Frankly, I dislike the idea of polarized plugs for general use. It breeds a flawed expectation in electrical engineers that they know which is live and which is neutral because they have it marked so on a schematic. No, you don’t know, because schematic is not the real world, and of course, some doofus will mix things up. It’s better to begin from the assumption that you have no idea which is which. In a device, it’s generally not necessary to make the distinction.
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