Differential capacitance (per unit area of @I03118@ or electrode; SI unit \(\text{F m}^{-2}\)) is given by \[C=(\frac{\partial Q}{\partial E})_{T,p,\mu _{i},...}\] where \(E\) is the potential of the electrode with respect to a @R05229@, \(\mu _{i}\) is a set of @C01032@ which are held constant, \(T\) is the @T06321@, \(Q\) is the @E01923@ (per unit area of @I03118@ or electrode), and \(p\) is the pressure.