1. The problem statement, all variables and given/known data A cylindrical air capacitor with a length of 12.2 m stores an amount of energy equal to 3.00E-8 J when the potential difference between the conductors is 4 V. Calculate the magnitude of the charge on each conductor. 2. Relevant equations V=(lambda)/(2*pi*epsilon_0)*ln(r_0)/(r) energy density=1/2*epsilon_0*E^2 3. The attempt at a solution I know the energy, length, and potential. I'm not given either the charge on the cylinder or the ratio of the radii of the inner/outer conductors, both of which are necessary in the formula. I suspect the additional information needs to come from the equation involving the energy, some new input from knowing the electric field. Any help would be greatly appreciated.