Temperature Coefficient of Resistance

Temperature:

When electric current passes through a conductor the temperature of the conductor increases due to collision of electrons with other electrons and with atoms and molecules of conductor. This temperature has a great effect on the resistance of the conductor and to find this effect a term is coined called temperature coefficient of resistance.  

Temperature coefficient of resistance:

Temperature coefficient of resistance tells us about the effect of temperature on the resistance of a material.It is given by the following equation

                                  α=(Rt-Ro)/Rot

                           where

 α=temperature coefficient

 Rt=resistance at temperature=t in centigrade

 Ro= resistance at temperature=0 in centigrade

Unit:

The unit of temperature coefficient of resistance is per centigrade.

Effect of temperature on the resistance of electrical materials:

Electrical materials are also classified into two major types on the basis of temperature coefficient of resistance. Materials whose resistance increases with the rise in temperature are said to have positive coefficient of temperature and they are called conductors. While materials whose resistance decreases with the increase in temperature and they start conducting electric current are said to have negative coefficient of temperature. These materials are insulators and semi-conductors.