Question

Conductors of electric toasters and electric iron are made of an alloy rather than a pure metal. Why ?

Hint:

Nichrome (Nickel + Chromium) is the most common alloy used for heating elements.

Answer 1

Why Are Heating Elements of Electric Toasters and Irons Made of Alloys Instead of Pure Metals?

Heating elements used in electric toasters, irons, heaters and similar appliances are generally made of alloys such as nichrome rather than pure metals. This is because alloys possess certain properties that make them more suitable for producing heat.

1. Higher Resistivity:
Alloys have higher electrical resistivity compared to pure metals. Since heat produced in a conductor is given by: \[ H = I^2 R t \] Higher resistance (R) results in more heat production for the same current. Therefore, alloys generate more heat efficiently.

2. High Melting Point:
Alloys generally have a higher melting point than pure metals. Heating elements become very hot during operation, so the material must withstand high temperatures without melting.

3. Do Not Oxidise Easily:
Alloys like nichrome do not oxidise (burn) easily at high temperatures. Pure metals may react with oxygen in air and get damaged, but alloys form a stable protective oxide layer that prevents further corrosion.

4. Durable and Long-lasting:
Alloys are mechanically stronger and more durable than many pure metals. This increases the life of the heating element.

Conclusion:
Conductors of electric toasters and irons are made of alloys because they have higher resistivity, high melting point, and greater resistance to oxidation. These properties make alloys more suitable and safe for use as heating elements compared to pure metals.