Multiple Choice
A copper wire has a diameter of dCu = 0.0400 cm,is 3.00 m long,has a resistivity of 1.72 * 10-8 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 diameter of dAl = 0.0200 cm,and a carrier density of 6.02 * 1028 electrons/m3.A current of 0.400 A flows through the copper and aluminum wires.What is the ratio of the current densities JCu/JAl in the two wires?
A) 0.25
B) 0.50
C) 2
D) 3
E) 4
Correct Answer:

Verified
Correct Answer:
Verified
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