the space between two concentric conductivity spheres is filled on one side of a diametral plane with dielectric constant K1 and on other side with dielectric of constant K2. the inner sphere of radius A has charge +q. show that the force on it perpendicular to this diametral plane is

 

                                                          (  (K1-K2)q^2 ) / 8 *(K1+K2)^2 *A*A

  

ans in words:(K1-K2 multiplied with q*q) whole upon (8*(K1+K2) square *A square