This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: roofner (bar784) Homework 15 Weathers (22202) 1 This printout should have 10 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A rectangular loop located a distance from a long wire carrying a current is shown in the figure. The wire is parallel to the longest side of the loop. 6 . 75cm 2 . 31 cm 21 . 8cm . 0672A Find the total magnetic flux through the loop. Correct answer: 8 . 62353 10 10 Wb. Explanation: Let : c = 6 . 75 cm , a = 2 . 31 cm , b = 21 . 8 cm , and I = 0 . 0672 A . c a b r dr I From Amp` eres law, the strength of the magnetic field created by the currentcarrying wire at a distance r from the wire is (see figure.) B = I 2 r , so the field varies over the loop and is directed perpendicular to the page. Since vector B is parallel to d vector A , the magnetic flux through an area element dA is integraldisplay B dA = integraldisplay I 2 r dA . Note: vector B is not uniform but rather depends on r , so it cannot be removed from the integral. In order to integrate, we express the area element shaded in the figure as dA = b dr . Since r is the only variable that now appears in the integral, we obtain for the magnetic flux B = I 2 b integraldisplay a + c c d r r = I b 2 ln r vextendsingle vextendsingle vextendsingle a + c c = I b 2 ln parenleftbigg a + c c parenrightbigg = (0 . 0672 A)(0 . 218 m) 2 ln parenleftbigg a + c c parenrightbigg = (0 . 0672 A)(0 . 218 m) 2 (0 . 294327) = 8 . 62353 10 10 Wb . 002 10.0 points A solenoid 8 . 7 cm in radius and 88 m in length has 13100 uniformly spaced turns and carries a current of 5 . 8 A. Consider a plane circular surface of radius 3 . 2 cm located at the center of the solenoid with its axis coincident with the axis of the solenoid. What is the magnetic flux through this circular surface?(1 Wb = 1 T m 2 ) Correct answer: 3 . 49041 10 6 Wb....
View Full
Document
 Fall '00
 Littler
 Magnetism, Work

Click to edit the document details