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 $\mathrm { A }$ is $1.68 \times 10 ^ { - 8 } \Omega \cdot \mathrm { m }$ , and the resistivity of metal $B$ is $1.59 \times 10 ^ { - 8 } \Omega \cdot \mathrm { m }$ .

A) $19 \mathrm {~mA}$
B) $21 \mathrm {~mA}$
C) $11 \mathrm {~mA}$
D) $5.3 \mathrm {~mA}$