A positively charged particle is held at the center of a spherical shell. The figure gives the magnitude E of the electric field versus radial distance r. The scale of the vertical axis is set by Es = 14.5 x 10 N/C. Approximately, what is the net charge on the shell? Assume Is = 3 cm. ES E (10' N/C) 0 Y'S 3T's 4r'S r (cm) Number Units