Changes

==Composition==

==Composition==

Heating elements are made from a conductive (though resistive) material—although other materials may be usable, metal is generally preferred.  They are usually made from alloys containing primarily either iron or nickel. One of the most common compositions uses  nichrome, an alloy of about 80 percent nickel and 20 percent chromium. Nichrome is a resistant conductor, does not oxidize regardless of temperature, has a very high melting temperature (about 2550&nbsp;°F), and expands very little when heated.  For these reasons it is a very good material for heating elements.  All other alloys used also must satisfy these basic requirements as well.  However, there are many other specific requirements, and resistance must be carefully calibrated.<ref name="explainthatstuff.com"/>

Heating elements are made from a conductive (though resistive) material—although other materials may be usable, metal is generally preferred.  They are usually made from alloys containing primarily either iron or nickel. One of the most common compositions uses  [[nichrome]], an alloy of about 80 percent nickel and 20 percent chromium. Nichrome is a resistant conductor, does not oxidize regardless of temperature, has a very high melting temperature (about 2550&nbsp;°F), and expands very little when heated.  For these reasons it is a very good material for heating elements.  All other alloys used also must satisfy these basic requirements as well.  However, there are many other specific requirements, and resistance must be carefully calibrated.<ref name="explainthatstuff.com"/>

==Types==

==Types==