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Unformatted text preview: Wong, Lemuel Homework 10 Due: Apr 4 2007, 5:00 pm Inst: Matt Mackie 1 This printout should have 17 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. The due time is Central time. NOTE the unusual due TIME: 5pm central, which is 6pm our time. this is meant to allow more time with the solutions before the exam. 001 (part 1 of 1) 10 points A wire carrying a current 30 A has a length . 1 m between the pole faces of a magnet at an angle 60 (see the figure). The magnetic field is approximately uniform at 0 . 5 T. We ignore the field beyond the pole pieces. I B What is the force on the wire? Correct answer: 1 . 29904 N. Explanation: Let : I = 30 A , = 0 . 1 m , = 60 , and B = 0 . 5 T . we use F = I B sin , so F = I B sin = (30 A) (0 . 1 m) (0 . 5 T) sin 60 = 1 . 29904 N . keywords: 002 (part 1 of 1) 10 points A wire carries a current of 8 A in a direction that make an angle of 31 . 5 with the direction of the magnetic field of strength 0 . 26 T. Find the magnetic force on a 5 . 79 m length of the wire. Correct answer: 6 . 29256 N. Explanation: Let : B = 0 . 26 T , I = 8 A , = 5 . 79 m , and = 31 . 5 . The magnetic force is F mag = B I sin = (0 . 26 T)(8 A)(5 . 79 m)(sin31 . 5 ) = 6 . 29256 N keywords: 003 (part 1 of 1) 10 points A circular loop of radius 3 . 95 cm contains 52 turns of tightly wound wire. If the current in the windings is 0 . 643 A and a constant magnetic field of 0 . 578 T makes an angle of 39 . 9 with a vector perpendicular with the loop, what torque acts on the loop? Correct answer: 0 . 0607644 N m. Explanation: Let : r = 3 . 95 cm , N = 52 , I = 0 . 643 A , B = 0 . 578 T , and = 39 . 9 . The torque acting on the loop is: ~ = NI ~ A ~ B Then  ~  = N I  ~ A  ~ B  sin = N I r 2 B sin = (52)(0 . 643 A) (0 . 0395 m) 2 (0 . 578 T)(sin39 . 9 ) = . 0607644 N m Wong, Lemuel Homework 10 Due: Apr 4 2007, 5:00 pm Inst: Matt Mackie 2 keywords: 004 (part 1 of 2) 10 points A circular current loop of radius R is placed in a horizontal plane and maintains a current I . There is a constant magnetic field ~ B in the xyplane, with the angle ( < 90 ) defined with respect to yaxis. The current in the loop flows counterclockwise as seen from above. I z k x y , B If the current in the loop is 0 . 276 A and its radius is 2 . 68 cm, what is the magnitude of the magnetic moment of the loop? Correct answer: 0 . 000622771 A m 2 ....
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This note was uploaded on 02/17/2011 for the course PHY 303L taught by Professor Turner during the Spring '08 term at University of Texas at Austin.
 Spring '08
 Turner
 Physics, Work

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