Why does the cord of an electric?

I think you mean why it gets warm, yeah?

It’s because of the electricity moving inside. The cord has copper wires. When electricity flows through them, it’s not a perfect journey. There is a bit of a fight, which is called 'resistance'. This resistance makes heat. It is normal for a cord to get a little bit warm. But if it gets proper hot, or smells like burning plastic, you must unplug it. That is a big danger sign, mate. It means something is very wrong with the wire or the plug.