1. The problem statement, all variables and given/known data In a Van de Graaff electrostatic generator, a rubberized belt 30 cm wide travels at a velocity of 20 meters/sec. The belt is given a surface charge at the lower roller, the surface charge density being high enough to cause a field of 40 statvolts/cm on each side of the belt. What is the current in milliamps? 2. Relevant equations I = nqua E= 4(pi)kq? 3. The attempt at a solution There might be some sort of Gaussian surface to be used here, I have the avg velocity (u), the area (a), the charge (q), just need the electrons per cubic centimeter to create such a field.