eli5: why do some plugs only have 2 flat prongs and others have a third cylindrical one?
In: 3
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.
Latest Answers