Question

The electrical resistivity of few materials is given below in ohm-metre. Which of these material can be used for making element of heating device?

A) $6.84\times {10}^{-8}$

B) $1.60\times {10}^{-8}$

C) $1.00\times {10}^{-4}$

D) $2.50\times {10}^{12}$

E) $4.40\times {10}^{-5}$

F) $2.30\times {10}^{17}$

Answer 1

Concept Used: Electrical Resistivity

Body of the solution:

1. The resistivity of the heating element must be moderate. The typical resistivity of metal is from ${10}^{-8}\mathrm{\Omega }\mathrm{m}\mathrm{to}{10}^{-6}\mathrm{\Omega }\mathrm{m}$. Insulators have resistivity ranges from ${10}^{12}\Omega mto{10}^{20}\Omega m$. Alloys have generally higher resistivity than their constituent metals and it is considered to be good for heating elements.
2. Therefore, D and F are insulators, A and B are good conductors, C and E are suitable materials for making element of heating device.