A cubic box with edge length of 4.6 m has its edges parallel with the xyz-axes. It is in an electric field:
E = ( 0.28 m-1 x + 0.84 ) i N/C,
where i is the unit vector along the x-axis. What is the net electric flux through the box in units of N m2 / C ?

Question

A cubic box with edge length of 4.6 m has its edges parallel with the xyz-axes. It is in an electric field:
E = ( 0.28 m-1 x + 0.84 ) i N/C,
where i is the unit vector along the x-axis. What is the net electric flux through the box in units of N m2 / C ?

anonymous · Answer

Put x = 0, and x = 4.6  Two values of E will be  obtained . Use flux = filed x area. At x= 0, filed lines are entering into the volume of the cube and at x = 4.6 they are leaving it. So, taking outward as positive we can find the net flux.

anonymous · Answer

outward flux = flux at x=4.6 , and inward flux = flux at x=0 .  Subtract the inward from outward flux and you'll get the answer.