E=j.row nd j=sigma.E ,Are these equations have same meaning if they are same them why we have derived it nd if different then why
In context to electrodynamics , row = Resistivity sigma=conductivity. Now we know Resistivity is the nature of a material to resist the flow of current where as Conductivity is the property of material to conduct current.
So , both equation have different implications. And we derive those differently so that we don't have to face any fundamental correlations.
Have a great eve!