 If you've ever looked at one of your outlets, you probably noticed that one of the slots is larger than the other, but you know the reason why, and you've certainly tried to plug something in, and the plug just wouldn't go, but if you flipped it around, it would go into the outlet just fine. But not all plugs are like this, some of them can be flipped around, and it doesn't matter which way they go in. So what's the reason behind the larger prong, and why do you need that bigger slot at all? Well in this video, I'm going to unlock the mystery and explain exactly why they're there. There's a plug that has one larger prong that's called a polarized plug, but as you know they're not all like this, and if we look at this transformer, both of these prongs are exactly the same size. Now our first cord had two prongs, and this one also has two, so why the difference? Well now if we look at this one that has a third prong which is a ground, this also has two prongs that are identical, and it doesn't have the larger plug at all. Now it's even more confusing, some plugs have the larger prong and other ones don't. Well it's all about how electricity flows inside your home. This electricity actually flows in and out of your outlet. Now when you plug something in you might have just thought you were using power, but to complete a circuit electricity comes out of the smaller prong, goes into your appliance, and then goes back into the larger prong of your outlet. The smaller slot is referred to as the hot, and the larger is called the neutral, and the reason they exist is for electrical safety, but it's easier to understand that if you can actually see it in action. Here's a typical household light with a polarized plug. Now this pen detects voltage and it lights up red anytime it senses electricity. Now it sees power up until the switch, but the switch is off, and now you can see it's green afterwards because there's no power present. But when I do the same test again with the light in the on position, you can see that it's red before and after the switch, and that's exactly how it should work. But what if I took that polarized plug and I filed off those little prongs so that they were both the same? Well actually I don't have to because I have this very illegal adapter that will take a polarized plug and turn it into a non-polarized plug. And now I can plug it in either way, so for the test I'm going to plug it in backwards so that the neutral and the hot are actually reversed. And now when I repeat the test, take a look, I've got power before the switch, but now I've also got power after the switch all the way to the lamp, but how is that possible because the switch is actually off? When we flip that plug around, we actually reverse the flow of electricity in our circuit. Power switches are only placed on the hot line of the circuit. That means when you switch something off, you stop the flow of power long before it gets to the appliance. But when we flipped it, we actually had the electricity now going through the line of the neutral into the appliance and then into the switch. This creates a very unsafe situation and it's kind of like driving the wrong way on the freeway. And by using a polarized plug, a manufacturer can guarantee that the circuit will be completed correctly and the hot and the neutral will end up in the right place. But then why does some cords still not use this setup and are they unsafe to use? Well, let's start by looking at this typical 3-prong cable. Now as we look, both of these prongs on top are exactly the same size and it's not polarized, but this plug has a little bit of a secret and that's this ground prong on the bottom. Even though the two prongs on top are identical, you can only plug this in in one direction. You can't flip this upside down. So even without the bigger prong, the neutral and the hot will still end up in the correct position. But then what about things like these AC adapters and iPhone chargers? They don't have that ground prong and the two prongs that are there are exactly the same size. And it's actually okay for a couple of reasons. First, unlike appliances, these are made of plastic and you're going to have metal on the outside that could give you a shock. And second, chargers reduce the amount of voltage coming out of your wall outlet to a much safer level. So putting a polarized plug on these type of devices wouldn't actually give you any benefit. But what about older things like lamps, electric shavers and even old Christmas lights are they actually safe to use? Well, the real answer is it depends. If they've got a metal body, you definitely run the risk of potentially getting an electrical shock if the device has any type of a problem. And the next time you go to plug something and it won't fit and you need to flip it upside down, at least you know that largest slot is there to help keep you safe and make sure your appliances are working correctly. Hope this video helped explain this a bit better. And if you liked it, please give me a thumbs up and subscribe to my channel if you're not already for more videos coming up.