Sea water at frequency $V=4\times {10}^{8}Hz$has permittivity $\in \approx 80{\in }_0$ , permeability $\mu \approx {\mu }_0$ and resistivity  $\rho =0.25\Omega -m$. Imagine a parallel plate capacitor immersed in sea water and driven by an alternating Voltage of $400V$ then the maximum conduction current density is  $\_\_\_\_\_\_\_Volt/ohm{m}^2$( distance between the plates , $d=1m$)