Question

The essential requirements for a good heating element are _ _ _ _ _ _ _ _ _ _ _ _ _.
A. High resistivity and low melting point
B. High resistivity and high melting point
C. Low resistivity and low melting point
D. Low resistivity and high melting point

Answer 1

The heating element is an electrical component used to convert electrical energy into thermal energy. In other words, we can say that the heating element is used to convert electricity into heat.

Complete step by step solution:
Resistivity is the resistance of that heating element having a unit cross-sectional area and unit length. The expression for resistivity gives us the relationship between resistance, cross-sectional area, and the given heating element's length. Mathematically, we can write:
$\partial = \dfrac{{RA}}{l}$
Here, R is the resistance, A is the cross-sectional area, l is the length, and $\partial$ is the resistivity of the heating element.

Based on the above expression, we can say that the heating element's resistivity is directly proportional to its resistance. We know that loss of electrical energy in terms of heat is directly proportional to the resistance, so high resistivity is the desirable property of a heating element.

The heating element is subjected to very high-temperature ranges, so it must have the ability to withstand higher temperature ranges. Therefore, the heating element should have a high melting point.

Therefore, high resistivity and high melting point are two essential requirements for a good heating element. Hence, option (B) is correct.

Note: Resistivity and melting point of a heating element depend on the material that means these are the material's properties. Make sure to take into account both resistivity and temperature while selecting a good heating element.