The figure shows two nonconducting spherical shells fixed in place. Shell 1 has uniform surface charge density +6.6 μC/m2 on its outer surface and radius 4.0 cm; shell 2 has uniform surface charge density +4.1 μC/m2 on its outer surface and radius 2.1 cm; the shell centers are separated by L = 13.3 cm. What is the x-component (with sign) of the net electric field at x = 2.0 cm ? Number Units