Question

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

A	6.84 × 10−8
B	1.60 × 10−8
C	1.00 × 10−4
D	2.50 × 1012
E	4.40 × 10−5
F	2.30 × 1017

​ Give reason for your answer.

Answer 1

The metals and alloys have very low resistivity in the range of 10^-8 Ωm to 10^-6 Ωm. So, they are a good conductor of electricity. While insulators have a resistivity of the order of 10¹² Ωm to 10¹⁷ Ωm. Alloys have generally higher resistivity than its constituent metals and consider good for the heating elements. So, elements C and E are best for making heating elements. While D and F are considered as an insulator and A and B are a good conductor of electricity.