$F_{ E }=\frac{k e^{2}}{r^{2}}$ $...(I)$

The expression for magnetic force is given by,

$F_{ M }=\frac{e^{2} V^{2} \mu_{0}}{4 \pi r^{2}}$ $...(II)$

Divide equation $(I)$ and $(I).$

$\frac{F_{ E }}{F_{ M }}=\frac{\frac{k e^{2}}{r^{2}}}{\frac{e^{2} V^{2} \mu_{0}}{4 \pi r^{2}}}$

$=\frac{k 4 \pi}{V^{2} \mu_{0}}$ $...(III)$

Substitute $9 \times 10^9$ for $k, 4.5 \times 10^{5} m / s$ for $V$ and $4 \pi \times 10^{-7}$ for $\mu_\circ$ in equation $(III).$

$\frac{F_{ E }}{F_{ M }}=\frac{9 \times 10^9 \times 4 \pi}{\left(4.5 \times 10^{5} m / s \right)^{2} 4 \pi \times 10^{-7}}$

$=4.4 \times 10^{5}$