V=I²R

When you pass a current through a material it heats up due to the resistance measured in ohms. This heat drives the process. (of sintering, melting, reduction, decomposition etc.)

Electric elements are usually long and made of various materials, such as nickel chromium (nichrome), kanthal wire, molybdenum, molybdenum disilicide , silicon carbide or carbon.

They can be wire, coiled wire, ribbons, tubes, spiral tubes or loops.

You don’t have to know much about them, but you should be able to recognise them.