Explain with the help of graph the variation of conductivity with temperature for a metallic conductor ?

Explanation

Conductivity of a metallic conductor `sigma=1/p=(ne^2r)/m`
With rise of temperature, the collision of electrons with fixed lattice ions/atoms increases so that relaxation time decreases. Consequently, the conductivity of metals decreases with rise of temperature. Figure represents the variation of conductivity of metal with temperature. Initially the variation of conductivity with temperature is linear and then it is non-linear