Point charge q sits at the center of a hollow metal sphere as shown above, where the inner radius is a = 8.00 cm and the outer radius is b = 14.5 cm. There is +7.10 nC distributed on the inner surface of the sphere and -19.7 nC on the outer surface. What is the magnitude of the electric field at a distance of 21.8 cm from the centre of the sphere?
1.49E+04 N/C
3.73E+03 N/C
0.373 N/C
0 N/C