Question

A solid metallic sphere of a radius a carries total charge Q.No other charges are nearby.The electric field just outside is surface is keQ/a squared radially outward. At this close point, the uniformly charged surface of the sphere looks exactly like a uniform flat sheet of charge. Is the electric field here given by o/e or o/2e?

Answer 1

The electric field just outside its surface is 

$$E=\frac{kQ}{a^2}$$

$$k=\frac{1}{4\pi \epsilon_0}$$

$$E=\frac{1}{ \epsilon_0}\frac{Q}{A}=\frac{\sigma}{ \epsilon_0}$$