When a Potential Difference Is Applied Across a Piece of Wire

Multiple Choice

When a potential difference is applied across a piece of wire made of metal A, a $5.0 - \mathrm { mA }$ 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, 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 × 10^-8 ? ? m, and the resistivity of metal B is 1.59 × 10^-8 ? ? m.

A) 21 mA
B) 19 mA
C) 11 mA
D) 5.3 mA