Answer
$E_c = 3.60\times 10^{-6}~N/C$
Work Step by Step
We can find the magnitude of $E_c$:
$E_c = \frac{1}{4~\pi~\epsilon_0}~\frac{\vert q \vert}{r^2}$
$E_c = \frac{1}{(4~\pi)~(8.854\times 10^{-12}~F/m)}~\frac{1.6\times 10^{-19}~C}{(0.0200~m)^2}$
$E_c = 3.60\times 10^{-6}~N/C$
