When a potential difference is applied across a piece of wire made of metal A, a 5.0 mA current flows. If the metal-A wire is replaced with a wire made of metal B having twice the diameter of the metal-A wire, find how much current will flow through the metal-B wire? The lengths of both wires are the same, and the voltage difference remains unchanged. The resistivity of metal A is 1.68 x 10-8 m, and the resistivity of metal B is 1.59 x 10-8 m.