Hi, I need help with a surface charge problem: The cylindrical drum of a copy machine is 40 cm long and has a radius of 5 cm. If charge is uniformly distributed over the curved surface of the drum, and the electric field near the surface is 2 x 10^5 N/C, estimate the amount of charge on the drum. I know you set the electric flux to Q/E0. I calculated the Q = o*2pi*r*L. Since electric flux E(2*pi*r*L) should cancel out 2pi*r*L when setting them both equally, leaving E=o/E0. However, i still keep getting the wrong answer. Thanks for the help.