Question Detail

Method (Gauss's law for a sphere): pick the Gaussian radius r = (2/3)R = (2/3)(0.135) = 0.09 m, then E = kQ_enclosed/r2. Caution: the numbers as PRINTED (Q = 10 C) are not physical for this option set - 10 coulombs at 9 cm would give E = (9x109)(10)/(0.09)2 ~ 1.1x1013 N/C, which matches none of the options. The charge was almost certainly meant to be in nano/micro-coulombs. The recorded key from the source is A (165 kN/C); use the method E = kQ/r2 with whatever charge value your lecturer's version of this question states.