A 0.380 m long cylindrical capacitor consists of a solid conducting core with a radius of 1.15 mm and an outer hollow conducting tube with an inner radius of 2.05 mm . The two conductors are separated by air and charged to a potential difference of 6.40 V . Calculate the charge per length for the capacitor. lambda =_______ C/m. Calculate the total charge on the capacitor. Q=_____ C. Calculate the capacitance. C=______ F. Calculate the energy stored in the capacitor when fully charged. U=_______ J. Well i figure out a couple of equations to use but i seem to get them wrong! all are wrong! Any Help! so the equation i used were : To Find C = 2 pi €o L ln(r2/r1) = 12.22 *10^-12 F = 12.22 pF. To Find U = (1/2) C V^2 = 250*10^-12 J = 250 pJ. To Find Q = C V = 78.2*10^-12 C = 78.2 pC To Find lambda = Q/L = 2.06*10^-10 C/m = 206 pC/m.