The @[email protected], \(u\) of the @[email protected] multiplied by the @[email protected], \(j\): \[\bar{u} = u\ j\] \[\bar{u} = \frac{F\ j}{\varepsilon_{\text{I}}}\] where \(F\) is the @[email protected], \(\varepsilon_{\text{I}}\) is the @[email protected]