Assignment:
Two conducting wires each of length L are connected to a knob, whereby a total electric charge Q is deposited onto two small spherical metallic spheres, each of mass m and diameter d, at the end of the wires. We observe each wire of this electroscope to lie at an angle q from the vertical.
Find an expression for the charge Q in terms of the given quantities L,m,d and q as well as physical constants. You have now calibrated the electroscope, and may use it for quantitative experiments.
q
L
Compute the electric field, in both components and as magnitude and direction, at the midpoint between the two hanging masses.