**Part A**

Potential difference:

$\overline{){\mathbf{V}}{\mathbf{=}}{\mathbf{I}}{\mathbf{R}}}$

Resistance, R:

$\overline{){\mathbf{R}}{\mathbf{=}}{\mathbf{\rho}}\frac{\mathbf{L}}{\mathbf{A}}}$

A = πr^{2}

r = d/2 = 1.628 /2 = 0.814 mm.

A 14.0 gauge copper wire of diameter 1.628 mm carries a current of 12.5 mA.

Part A

What is the potential difference across a 2.00 m length of the wire (for copper ρ = 1.72 × 10^{-8} Ω • m)?

Part B

What would the potential difference in part (a) be if the wire were silver instead of copper, but all else was the same (for silver ρ = 1.59 ×10^{-8} Ω • m)?

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