Defined by the equation: \[\delta = \frac{D}{k_{\text{d}}}=\frac{n\ F\ D\ c\ A}{l_{i}}\] where \(D\) is the @D01719@, \(k_{\text{d}}\) is the @H02805@, \(F\) is the @F02325@, \(c\) is the concentration, \(A\) is the geometric area of the electrode, \(l_{i}\) is the @L03532@ and \(n\) is the @C00995@.