# Equation to relate voltage to distance of a spark

I need to calculate the minimum distance for which a charge of some voltage will jump. Is there any equation that relates distance of a spark jump to voltage (a fairly generalised equation will do, I dont need to worry about strange shapes of the charged bodies that the charge leaps between or anything). Assume that this occurs in a vacuum. (This isnt homework, just part of a side project, and I am stuck because I cant figure out the above sub-problem, which hopefully isnt too difficult).