Electrical resistivities of some substances, in ohm-meter, at 20°C are given as follows :

Question

Electrical resistivities of some substances, in ohm-meter, at 20^oC are given as follows :

Silver	1.60 x 10-8
Copper	1.62 x 10-8
Tungsten	5.2 x 10-8
Mercury	94 x 10-8
Iron	10 x 10-8
Nichrome	10 x 10-6

(i) Out of the silver and copper, which is a better conductor of electric current and why ?

(ii) Which substance is preferred to be used for electrical transmission lines ? Give reason.

(iii) Name the material that you would advise to be used in the heater elements of electric heating device and why ?

Answer 1

(i) Silver is a better conductor, lower resistivity.

(ii) Copper, economical/low resistivity.

(iii) Nichrome; Very high resistivity/ as it is an alloy, it does not oxidize readily at high temperature.