Which of the following metals is used for the manufacture of heating elements provided in electric iron?
(1) Nickel
(2) Chromium
(3) Nichrome
(4) Tungsten
Answer: (3) Nichrome is the most common domestic heating element and is found in many household products. Commonly, items such as toasters, hairdryers and heaters use nichrome coils to pass electricity and give off heat. Nichrome is made of 80 per cent nickel and 20 per cent chromium, and its high melting point of 1,400 degrees Celsius. Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. Due to its relatively high electrical resistivity and resistance to oxidation at high temperatures, it is widely used in electric heating elements, such as in hairdryers, electric ovens, soldering iron, toasters, and even electronic cigarettes.
