An electron with kinetic energy $$5 \mathrm{~eV}$$ enters a region of uniform magnetic field of 3 $$\mu \mathrm{T}$$ perpendicular to its direction. An electric field $$\mathrm{E}$$ is applied perpendicular to the direction of velocity and magnetic field. The value of E, so that electron moves along the same path, is __________ $$\mathrm{NC}^{-1}$$.

(Given, mass of electron $$=9 \times 10^{-31} \mathrm{~kg}$$, electric charge $$=1.6 \times 10^{-19} \mathrm{C}$$)

In an alpha particle scattering experiment distance of closest approach for the $$\alpha$$ particle is $$4.5 \times 10^{-14} \mathrm{~m}$$. If target nucleus has atomic number 80 , then maximum velocity of $$\alpha$$-particle is __________ $$\times 10^5 \mathrm{~m} / \mathrm{s}$$ approximately.

($$\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \mathrm{SI}$$ unit, mass of $$\alpha$$ particle $$=6.72 \times 10^{-27} \mathrm{~kg}$$)