It is called as the HEATING ELEMENT
usually they can be seen in iron boxes,geysers and etc..
they are usually made of semi conducting metals like nichrome or cupronickel
Heating elements for high-temperature furnaces are often made of exotic materials, including platinum, molybdenum disilicide, molybdenum (vacuum furnaces) and silicon carbide. Silicon carbide igniters are common in gas ovens.
Early electric stoves used tubular heating elements for all functions, but some are using other technology for the surface burners to produce a smooth-top range that is easier to clean.