The electric field in a region is given by $\;\overrightarrow{E}=\alpha\;x^2 \hat{i}\;$ Here $\;\alpha\;$ is a constant of proper dimensions . Find the total flux passing through a cube bounded by the surfaces . $x=l\;,x=2l\;,y=0\;,y=-l\;,z=0\;,z=l\;.$

Question

$(a)\;\alpha\;l^4\qquad(b)\;2\;\alpha\;l^4\qquad(c)\;3\;\alpha\;l^4\qquad(d)\;4\;\alpha\;l^4$