Answer
$E = 1.25~N/C$
Work Step by Step
When $v = 0$, the force on the electron due to the magnetic field is zero.
Therefore, when $v=0$, $~~F_{net} = F_E$
We can find the magnitude of the electric field:
$F_E = \vert q \vert~E = 2\times 10^{-19}~N$
$E = \frac{2\times 10^{-19}~N}{\vert q \vert}$
$E = \frac{2\times 10^{-19}~N}{1.6\times 10^{-19}~C}$
$E = 1.25~N/C$
