Acopper ball of mass 123 g is positively charged to +479 c. it is hung from a metal plate by a plastic, insulating spring of equilibrium length 29 cm and stiffness 2.1 n/m (1) if the plate is not charged, what is the extended length of the spring after the ball is suspended from it? (2) using standard data for copper, estimate the number of atoms there are in the ball per excess electron that charges it. atoms/e (3) if the plate is attached to a power supply and the ball raises back to its equilibrium length, what is the magnitude of the electric field puts out?