The relation between current and drift velocity of electron is
$\mathit{I}=\mathit{n}\mathit{e}\mathit{A}{\mathit{v}}_{\mathit{d}}$




${\mathit{v}}_{\mathit{d}}=\frac{\mathit{e}\mathit{E}}{\mathit{m}\mathit{l}}\mathit{\tau }$



$\therefore \mathrm{}\mathit{I}=\mathit{n}\mathit{e}\mathit{A}\times \frac{\mathit{e}\mathit{V}}{\mathit{m}\mathit{l}}\mathit{\tau }$
$\mathit{R}=\frac{\mathit{V}}{\mathit{I}}=\frac{\mathit{m}\mathit{l}}{\mathit{n}\mathit{A}{\mathit{e}}^2\mathit{\tau }}$
As the temperature increases, the number of collisions increases and $\mathit{\tau }$ decreases and hence the resistance increases.