Conducting materials

Solids are classified into three-conductors, semiconductors and insulators. In conducting materials, for example metals, valence electrons are free to move about the lattice and are known as free electrons. Whenever these free electrons suffer scattering, resistivity rises. There are two causes for scattering. They are scattering due to impurities present in the sample and scattering due to lattice ion vibrations. Conducting materials possess very feeble resistivity and high conductivity. Power loss and voltage drop are very less in these materials. Temperature co-efficient of resistance is very low for conducting materials. They are highly ductile and malleable. Soldering and welding of conducting materials are easy. Conducting materials are normally very strong and can withstand stress and strain. Conducting materials have high resistance to corrosion when exposed to atmosphere. Some examples of conducting materials are Aluminium, Brass, Bronze, Copper, Gold, Mercury, Silver and Zinc. Commonly used conducting materials are Copper, Aluminium, Brass and Bronze. High resistance conducting materials like tungsten, manganin, constantan, nichrome, carbon, platinum and mercury are used in electric lamp filaments, electron tube heaters, radars, electronic valves, rheostats and motor starters.