E(r) 2 仍然定义电势0点为V(a)=0,则可通过计算场的积分来计算电势差 F>a时 (r)=-E(r)d 2Te n in( r≤a时 (r)=E( dr r 2e a 4e a 4丌Ena 28 2 eal case V(o Inside Outside-In(r) 思考:考虑电荷分布在柱子表面一个薄层的情形下空间的电势分布0 2 0 0 ( ) , 2 2 E rr r r a a ρ λ ε πε = ⋅ = < ~1/r ~r E r 仍然定义电势 0 点为 V a() 0 = ，则可通过计算场的积分来计算电势差： r a > 时 0 () ( ) 2 r r a a V r E r dr dr r λ πε =− ⋅ =− ⋅ ′ ′ ′ ′ ∫ ∫ 0 0 ln ln( ) 2 2 r a a r r λ λ πε πε =− = ′ r a ≤ 时 2 2 2 0 0 () ( ) 2 4 a a a r r r V r E r dr r dr r a a λ λ πε πε == = ′ ′ ′′ ∫ ∫ ′ 2 2 2 2 0 0 1 ( ) [1 ( 4 2 2 r a r a a ) ] λ λ πε πε = −= − V(r) r Inside~r2 Outside ~ ln(r) ideal case 思考：考虑电荷分布在柱子表面一个薄层的情形下空间的电势分布