Answer
$q=0.32\mu C$
Work Step by Step
We know that;
$q=\sigma A=\sigma \pi Dh$
$\implies q=\pi \epsilon_{\circ}EDh$
We plug in the known values to obtain:
$q=3.1416(8.85\times 10^{-12})(2.3\times 10^5)(0.12)(0.42)=3.2\times 10^{-7}=0.32\times 10^{-6}=0.32\mu C$
