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Chapter 27 - 27.16

10 3 A .

(b) The cross-sectional area is A = πr 2 = 4 πD 2 . Thus, the magnitude of the current density vector is

10 − 3 Ω=1 . 53

J = i

A =

4 i

πD 2 =

4(1 . 53

10 − 3 m) 2 =5 . 41

10 − 3 A)

10 7 A / m 2

π (6 . 00

10 − 3 Ω)( π )(6 . 00

10 − 3 m) 2 / [4(4 . 00m)] = 10 . 6

10 − 8 Ω

m .

Thematerialisplatinum.

16. (a) i = V/R =23 . 0V / 15 . 0