8_Ch 17 College Physics ProblemCH17 Current and Resistance

8_Ch 17 College Physics ProblemCH17 Current and Resistance...

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76 CHAPTER 17 17.8 Assuming that, on average, each aluminum atom contributes one electron, the density of charge carriers is the same as the number of atoms per cubic meter. This is A A density N n mass per atom M N M ρ == = , or ( ) ( ) ( ) 23 3 6 3 3 28 3 6.02 10 mol 2.7 g cm 10 cm 1 m 6.0 10 m 26.98 g mol n  ×  × The drift speed of the electrons in the wire is then () 4 28 3 19 6 2 5.0 C s 1.3 10 m s 6.0 10 m 1.60 10 C 4.0 10 m d I v neA −− = × ×× × 17.9 (a) The carrier density is determined by the physical characteristics of the wire, not the current in the wire. Hence, n is unaffected . (b) The drift velocity of the electrons is
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This note was uploaded on 12/09/2011 for the course PHYS 2020 taught by Professor Staff during the Fall '10 term at FIU.

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