please answer this :

Question

A conducting sphere of radius 0.01 m has a charge of 1.0  10^–9 C deposited on it. The

magnitude of the electric field in N/C just outside the surface of the sphere is:

A) zero

B) 450

C) 900

D) 4500

E) 90,000

Answer 1

For a conducting sphere the charge is uniformly distributed over its surface and for finding field just outside the surface the equivalent charge may be supposed to be located at the center of sphere

So

E = KQ/r²

Where K = 9*10⁹

For just outside r = R = radius of sphere

E = 9*10^{9 *} (10^-9 ) / (0.01)² N/C

= 9* 10^{9 *} 10 ^-9/ 10 ^-4 N/C