Question

Why are alloys commonly used in electrical heating devices?
(a) Due to high resistivity
(b) Due to low resistivity
(c) Due to high elasticity
(d) Due to medium resistivity

Answer 1

Hint: In this question the concept is that alloys are generally known for high resistivity and high melting point. This adds up the application of alloys in heating devices. This approach will help get the right answer to this problem statement.

Complete Step-by-Step solution:
As we know alloys have high resistivity and high melting point as compared to pure metals.
So alloys cannot easily burn or oxidize at higher temperature.
Now as we want higher temperature in heating devices so we use alloys in heating devices.
For example: Nichrome which is the combination of nickel and chromium.
Alloys are, for example: Nichrome, generally harder than pure metals.
They are made up of atoms of different sizes, rather than being uniform.
This means that the layers of atoms cannot slide over each other easily, making the whole alloy much stronger than any of the pure metals that the alloy contains in isolation.
Advantages of alloys:
$\left( i \right)$ Enhance tensile strength.
$\left( {ii} \right)$ Enhance corrosion resistance.
$\left( {iii} \right)$ Enhance the hardness of the metal.
$\left( {iv} \right)$ Modify color
$\left( v \right)$ Provide better cast ability.
So this is the required answer.
Hence option (A) is the correct answer.

Note – Free electrons are scattered off imperfections and alloys have many more of them than pure metals. The higher resistivity in alloys as compared to the constituents is caused by an additional scattering mechanism of the electrons called "alloy scattering". This explains the increased resistivity of alloys.