Electric field of charge continuously distributed The superposition law for electric field For a charged line segment: 线电荷： dq Aal Surface: 面电荷：dg=ods Volume: 体电荷 dq pdv Electric field of charge continuously distributed The superposition law for electric field For a charged line segment： Surface： Volume： 线电荷： dq  dl 面电荷： dq ds 体电荷 ： dq  dV