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Unformatted text preview: Create assignment, 00224, Homework 5, Feb 28 at 6:39 pm 1 This print-out should have 9 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. Lengthening a Wire 02 27:03, trigonometry, numeric, > 1 min, nor- mal. 001 A wire with a resistance R is lengthened to 1 . 25 times its original length by pulling it through a small hole. Find the resistance of the wire after it is stretched. Correct answer: 1 . 5625 R . Explanation: Let : = 1 . 25 . The volume V of the wire is given by V = A, where is the length of the wire and A is the cross-sectional area. When the wire is stretched to a length , the volume will re- main the same. The new cross-sectional area is then, A = A A = A = A 1 . 25 = A 1 . 25 . The resistance of a conductor of resistivity is given by R = A , so R R = A A = A A = (1 . 25 ) A A 1 . 25 = (1 . 25) 2 . Thus R = (1 . 25) 2 R = 1 . 5625 R . keywords: Serway CP 17 64 27:03, trigonometry, numeric, > 1 min, nor- mal....
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