eli5: why do some plugs only have 2 flat prongs and others have a third cylindrical one?
In: 3
The bottom one is ground.
The ground is to prevent a short from electrifying the case. Imagine a metal toaster. It would be quite dangerous if there was a short, so you will always find a ground plug on a toaster, to increase safety.
If you build a different device, with no metal exposed parts, then you don’t need a ground.
The third cylindrical one is the grounding. I assume the 2 only plugs 🔌 are not ground needed. Besides that, there are some standards that change over time: for example here in my country there are 3/4 kinds of plugs because of standards change.
The three prongs are hot, neutral, and “ground.”
The “ground” is not required (though should be, imo) in all devices as the neutral is usually enough to act as a “ground” unless it is a very powerful device.
The third prong is there to help create a connection between the electricity and the ground that isn’t you in the event that electricity goes somewhere it shouldn’t.
The optional one is ground. It connects to all the metal parts on the thing you’re plugging in, and in the wall it connects to the actual ground (like, the ground you walk on).
By wiring all metal parts to the ground it prevents any possibility of electric charge building up on them. It helps make sure that if something goes wrong the breaker turns off instead of you getting electrocuted, and it also prevents static electricity buildup and sometimes reduces the possibility of radio interference.
If the thing doesn’t have metal parts, then the ground connection doesn’t do anything.
Some things like phone chargers do have metal parts but they’re built in an extra-safe way to make sure electricity doesn’t leak. Those are also allowed to not have a ground connection. Although IMHO having a ground connection is a sign of a slightly higher quality product.
The 2 flat prongs are the actual circuit prongs that carry the power to make the thing work.
By the way they have different shapes in other countries.
3 prongs = increased safety. 3rd prong is especially used for stuff that uses lots of electricity, because increased danger to user
Electricity flows in a circuit into the right prong (hot) and out of the left prong (neutral). The 3rd prong is called the ground and it’s identical to the left/neutral. It’s a backup to keep you getting shocked if something happens to the neutral plug – it’s a 2nd option for the electricity to flow out instead of into you
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