A charge q kept in front of a neutral metallic sphere. Find the electric field at the centre of sphere due to the induced charges on the surface of the sphere shown.

Strategy `:` The net electric field inside the conductor is zero. This is produced by induced charges and the external charge.

Explanation

`E_("induced ")+ E_(q)= implies E_("induced")= (q)/(4pi epsilon_(0)d^(2))`