What kind of element heats up the blade in hair straighteners?

Answer 1

At the heart of most hair (and other) appliances that have heaters is nichrome™ wire. Nickel chromium alloy wire makes a good resistive heating element, and it is probably tucked inside more things that heat than you can imagine. The way nichrome is packaged usually involves coiling the wire and surrounding it with a ceramic material. This electrically insulates it from an outer package and provides a method of conducting the heat out of the wire and to the working surface of the device. The outer packaging could be metal, like in the heating elements of a traditional electric range. In toasters, hair dryers and the like, the "raw" nichrome can be seen glowing inside the appliance. It is mechanically suspended in there by (usually) mica insulators. In the hair straitener, the large flat working surface is usually either aluminum or ceramic. In either case, the nichrome wire heating element is tucked unside there somewhere. The difference in price between the ceramic hair straitner and the other one reflects the fact that aluminum is much easier to work than the ceramic material, and many companies are completely tooled up to manufacture things out of aluminum while not quite so many are set up to make things from ceramics. Got a link to Wikipedia's post on nichrome if you want it.