A small sphere with a mass of 2.00×10−3 g and carrying a charge of 5.20×10−8 C hangs from a thread near a very large, charged insulating sheet, as shown in the figure . The charge density on the sheet is −2.40×10−9 C/m^2.

Question

Find the angle of the thread.

Answer 1

forces: mg downward, E*q=k*sigma*q

tanTheta (angle from vertical)= k*sigma*q/mg

where k= 1/2epislion