The cylindrical Capacitor(柱形电容器) By Gauss's law: E 2m8,rl s-E-2 qdr △U= R 2πE R capacitance C=. 2π61 △U In Rg/RaThe cylindrical Capacitor（柱形电容器） l RA By Gauss’s law： RB A B o R R l q U ln 2    h r B A o R R l U q C ln 2    capacitance 