Conducting materials are those materials which offers easy path to the flow of electric current. It offers low resistance to the flow of current. Silver, Copper, Aluminium, iron are the example of conducting materials. Conducting materials are subdivided into low resistivity and high resistivity materials.
Low Resistivity Materials
There are the materials which offers low resistance to the flow of electric current through them. In order words, we can say that current can easily flow in these materials.
Low resistivity materials are used in house wiring, as conductors for power transmission and distribution of an electric power, in windings of electric machines like transformer, motors and generators. Basically, these materials are used where low power losses and voltage drops are required.
List of low resistivity materials are given below
Copper and Aluminium are used commercially because these materials have low resistivity and high conductivity. The conductivity of copper is higher than aluminium but due low cost of aluminium these are used in most of applications. Iron is used basically for manufacturing of earth wire or ground wire. The resistivity of iron is very high as comparatively to copper and aluminium.
Properties of Low Resistivity Materials
- It should have low temperature coefficient.
- The mechanical strength should be high.
- The material should be ductile which allow it to be drawn out into a wire.
- These materials should be such that it is not corroded when used in out-door services.
High Resistivity Materials
These materials are used for making resistance elements for heating devices filaments of lamps, rheostats etc. High resistivity materials are used in all such applications where a large value of resistance is required.
Tungsten, Nichrome etc are the examples of high resistivity materials.
Properties of High Resistivity Materials
The high resistivity materials should have following properties.
- These materials should have low temperature coefficient of resistance.
- These materials should have high meeting point. So it can withstand high temperature for a long time without melting.
- It should be able to withstand high temperature for a long time without oxidation.
- These materials should be ductile.
- High resistivity materials should have high tensile strength.