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Chapter 27 - 27.13

13. The resistance of the wire is given by R = ρL/A ,where ρ is the resistivity of the material, L is the

length of the wire, and A is its cross-sectional area. In this case,

A = πr 2 = π (0 . 50

10 − 3 m) 2 =7 . 85

10 − 7 m 2

Thus,

ρ = RA

= (50

10 − 3 Ω)(7 . 85

10 − 7 m 2 )

=2 . 0

10 − 8 Ω

m .

2 . 0m