Temperature Coefficient of Resistance:

Temperature coefficient of resistance, α  (alpha), is declared as the amount of modify of the resistance of a material for a given modification in temperature.  A positive value of denotes in which R increases along with temperature; a negative value of denotes R decreases; and zero denotes which R is constant.  Classical values are listed in Table 2.

For a given material, may vary with temperature; therefore, charts are often used to describe how resistance of a material varies with temperature.

An increase in resistance can be approximated from equation (2-2).

R_t =  R_o +R_o(αΔT)                       (2-2)

where

R_t = higher resistance at higher temperatures

R_o = resistance at 20^oC

α = temperature coefficient

T = temperature rise above 20^oC