A conducting sphere with a radius R is electrically neutral. An electric dipole is placed on both sides of the sphere. The center of the dipole is located at the spherical center O, namely, the distance from +q, or -q to the point O is a, as shown in figure. (a) Determine the electric field and potential generated by the induced charges at point O. (b) Remove-q, then the conducting sphere is connected to Earth (grounded), find the induced charge q' on the surface of the conducting sphere. R +q il a