An electron revolves around an infinite cylindrical wire having uniform linear charge density $2 \times 10^{-8} \mathrm{C} \mathrm{m}^{-1}$ in circular path under the influence of attractive electrostatic field as shown in the figure. The velocity of electron with which it is revolving is ___________ $\times 10^{6} \mathrm{~m} \mathrm{~s}^{-1}$. Given mass of electron $=9 \times 10^{-31} \mathrm{~kg}$