For a metallic wire, the ratio (V)/(i) ( V= applied potential...

The resistance of a metallic wire at temperature $t^{\circ} \mathrm{C}$ is given by $R_t=R_0(1+\alpha t)$ where $\alpha$ is coefficient of expansion. Hence, resistance of wire increases on increasing the temperature. Also, from Ohm's law, ratio of $\frac{V}{i}$ is equal to $R$ ie, $\frac{V}{i}=R$ Hence, on increasing the temperature the ratio $\frac{V}{i}$ increases.