Equation relating limiting current at a rotating disc electrode (see hydrodynamic voltammetry) to the amount concentration of an electroactive substance in bulk solution $c_0$, $$I_{\mathrm{l}\mathrm{i}\mathrm{m}}=kzFA{D}^{2/3}{\omega }^{1/2}{\nu }^{-1/6}{c}_0$$ where $k$ is a numerical factor, $z$ the electron number of an electrochemical reaction, $F$ the Faraday constant, $A$ the electrode surface area, $D$ the diffusion coefficient of the electroactive substance, $\omega$ the angular velocity (rotation rate), and $\nu$ the kinematic viscosity of the solution.