Resistivity of a resistor at a temperature $T$ is given by the relation:

$\rho \left(T\right)={\rho }_0\left[1+\alpha \left(T-T_0\right)\right]$

Where $\alpha$ is the temperature coefficient of resistivity, ${\rho }_0$ is resistivity at initial temperature $T_0$

$I$ and $V$ are respectively the current and voltage in a metal wire of resistance $R.$ The $I-V$ graph for the two different temperatures $T_1$ and $T_2$ are given, then

When the temperature of a conductor increases, the ratio of conductivity and resistivity _____

In an experiment, the resistance of a material is plotted as a function of temperature (in some range). As shown in the figure, it is a straight line.

One may conclude that