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 20oC 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.