$18.1 Conductors in electric field For a conductor of arbitrary shape, the electric field at its surface has the greatest magnitude near those portions with the smallest radius of curvature O 4Enr4兀E0R O E r aTer E 47e R E R e R ER O/P=T q $18.1 Conductors in electric field 5. An isolated conductor with cavity If there are no charges in the cavity, then the all charges on the conductor will reside on the out surface of the conductor The electric field Gaussian inside the cavity is zero Ei.ds=ods=0 0 Gaussian4 r R Q R q r E E R r Q q R Q E r q E R Q r q V R r r R = = = = = = = 2 2 2 0 2 0 0 0 / / ; 4 4 4 4 πε πε πε πε R r Q q For a conductor of arbitrary shape, the electric field at its surface has the greatest magnitude near those portions with the smallest radius of curvature. §18.1 Conductors in electric field 5. An isolated conductor with cavity If there are no charges in the cavity, then the all charges on the conductor will reside on the out surface of the conductor. The electric field inside the cavity is zero. 0 d 0 1 d S 0 in = ⋅ = = ∫ ∫ σ σ ε E S S S r r §18.1 Conductors in electric field