Why are alloys commonly used in electrical heating devices?
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Solution
Heating effect of electric current
When an electric current is supplied to a purely resistive conductor, current accumulates slowly and dissipates as heat. This effect causes heating of the resistor, which is known as the heating effect of electric current. Electric appliances like electric iron, electric kettle, electric toaster, electric oven, room heaters, and water heaters work on this principle.
The material used to create the heating effect must have higher resistance than pure metal to the flow of current. They must also have a high melting point to withstand the heat generated. As alloys have the desired property, they are used to design heating elements for different applications.
Nichrome (80% Nickel, 20% Chromium) is the most common alloy used for making heating elements for electrical appliances. Because nichrome does not oxidize and burn easily at high temperatures It has higher resistivity. Therefore lead to the dissipation of heat.
Cupronickel (CuNi) alloys are employed for low-temperature heating.
Explanation
Electrical heating devices work on heating effect of electrical current. The heating effect is high with high resistivity materials. Alloys have high resistivity and high melting point than pure metals. Alloys do not oxidize easily even at higher temperature. Hence they find applications in design of heating devices.
