$\mathrm{J}=$ current density

$=\frac{\mathrm{I}}{\pi \mathrm{r}^{2}}=\frac{1.7}{\pi \times\left(0.51 \times 10^{-3}\right)^{2}}=\mathrm{nev}_{\mathrm{d}}$

$=8.5 \times 10^{27} \times\left(1.6 \times 10^{-19}\right) \times v_{d}$

$\therefore $ $\mathrm{v}_{\mathrm{d}}=\frac{1.7}{\pi \times\left(0.51 \times 10^{-3}\right)^{2} \times 8.5 \times 10^{27} \times 1.6 \times 10^{-19}}$

$=1.5 \times 10^{-3} \mathrm{\,m} / \mathrm{sec} .=1.5 \mathrm{\,mm} / \mathrm{sec}$