Question

In the figure below, a butterfly net is in a uniform electric field of magnitude E = 5.5 mN/C. The rim, a circle of radius a = 20 cm, is aligned perpendicular to the field. The net contains no net charge. Find the electric flux through the netting.
N

Answer 1

Gauss' Law ?E=?E? ?dA? 3. The attempt at a solution At first I thought this was a simple problem. I reasoned that the net electric flux (?E) was zero because all the electric field lines that enter leave also. However, the book answer was not zero and so proved that answer wrong. Then I thought to just evaluate the electric flux noting that the the E? and A? point in the same direction so that, ?E=?E? ?dA? ?E=?|E? ||dA? |cos? Where, ?=0\textcolor[rgb]1.00,1.00,1.00.degrees Since, E? and A? point in the same direction. So, ?E=|E? |?|dA? | {{\Phi}_{E}} = {|\vec{E}|}{|{\vec{A}}}|} Where A>0, so letting, {|{\vec{A}}}|} = A. Noting that A=?a2. ?E=|E? |A ?E=|E? |?a2

Reference https://www.physicsforums.com/threads/gauss-law-why-the-opposite-sign.188507/