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Unformatted text preview: GenericStudent Homework 5 savrasov 39823 Jan 02, 2008 1 This print-out should have 5 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. 001 (part 1 of 1) 2 points Calculate the average drift speed of electrons traveling through a copper wire with a cross- sectional area of 40 mm 2 when carrying a current of 5 A (values similar to those for the electric wire to your study lamp). Assume one electron per atom of copper contributes to the current. The atomic mass of copper is 63 . 5 g / mol and its density is 8 . 93 g / cm 3 . Avogadros number N A is 6 . 02 10 23 . Correct answer: 9 . 22817 10- 6 m / s. Explanation: Let : N = 1 , M = 63 . 5 g / mol , = 8 . 93 g / cm 3 , A = 40 mm 2 = 4 10- 5 m 2 , I = 5 A , and q e = 1 . 6 10- 19 C / electron . We first calculate n , the number of current- carrying electrons per unit volume in copper....
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This note was uploaded on 01/10/2010 for the course PHY na taught by Professor Richardscalettar during the Winter '09 term at UC Davis.
- Winter '09