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Unformatted text preview: Physics 21 Fall, 2009 Solution to HW-13 28-12 Two parallel wires are 5.00 cm apart and carry cur- rents in opposite directions, as shown in the figure. Find the magnitude and direction of the magnetic field at point P due to two 1.50-mm segments of wire that are opposite each other and each 8.00 cm from P . d l r-r' d l r-r' Use the Biot-Savart Law: d B = 4 Id l ( r- r ) | r- r | 3 , where d l points in the direction of the current I , and r- r points from the current point to the field point ( P ). We can evaluate d B top and d B bottom (the contributions to the total field from the top and bottom wires, respectively) separately and then add them. The diagram shows the vec- tors d l and r- r for each of these contributions. The simplest way to evaluate the cross product is to use the right hand rule for the direction, and to get the magnitude from the products of the magnitudes | d l | and | r- r | and the sin of the angle between the vectors....
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This note was uploaded on 11/06/2009 for the course PHYS 21 taught by Professor Hickman during the Spring '07 term at Lehigh University .
- Spring '07