Right, in this demonstration we're going to show what happens when a large current flows through a conductor. In this case for conductor is copper. This is not a sensible thing to do. Do not do this at home. I'm doing it in reasonably controlled circumstances. So let's have a look. The car battery is going to provide a large current and we'll see if we can spot anything happening to the wire. You might have to watch quite carefully. Three, two, one, go. Now, as you can see, a large current not only has melted the wire, it's actually fused to the copper into the terminal of the battery. So a large current definitely has a heating effect. So now we're going to repeat the experiment with a more common conductor. This is a piece of mains cable found in your bedside lamp or something. And let's see what happens when a large current flows through this. I'm actually quite nervous about this. I've never done this before. I don't actually know what's going to happen, but I would guess it's not going to be good. Let's have a look. Okay. That's genuinely not a good thing. So what's happened there is the very high current has vaporised the plastic and what you heard was that gas is streaming out the end of the conductor. So that's what would happen if you short-circuited your domestic cabling without a fuse to protect you.