You are somewhat mistaken. You are thinking of the skin effect. In DC power, current flow is proportional to the cross section. As the frequency increases, the

You are somewhat mistaken. You are thinking of the skin effect. In DC power, current flow is proportional to the cross section. As the frequency increases, the effective resistance in the interior increases relative to the surface. At high enough frequencies, conductors effectively conduct only along the surface. See https://en.wikipedia.org/wiki/Skin_effect https://en.wikipedia.org/wiki/Skin_effect and https://en.wikipedia.org/wiki/Litz_wire https://en.wikipedia.org/wiki/Litz_wire .