A Copper Wire Has a Diameter of D_Cu = 0 $\varOmega$

question 43

Multiple Choice

A copper wire has a diameter of d_Cu = 0.0400 cm,is 3.00 m long,has a resistivity of 1.72 * 10^-8 $\varOmega$ m and has a carrier density of 8.50 * 10²⁸ electrons/m³.The copper wire is attached to an equal length of aluminum wire with a a carrier density of 6.02 * 10²⁸ electrons/m³.A current of 0.400 A flows through the copper and aluminum wires.If the ratio of the current densities the two wires,J_Cu/J_Al is 0.50,what is the diameter of the aluminum wire?

• A)0.0800 cm
• B)0.0283 cm
• C)0.0200 cm
• D)0.0565 cm
• E)0.0400 cm