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Unformatted text preview: Arb, Kellen Homework 15 Due: Oct 6 2004, 4:00 am Inst: Turner 1 This print-out should have 13 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 2) 10 points A positively charged particle enters a mag- netic field, as shown in the figure below. What is the initial direction of deflection? + + + + + + + + + + B in k j i ^ ^ ^ 1. F =- 2. F = + k 3. F = + correct 4. k ~ F k = 0, no deflection 5. F =- k 6. F = + 7. F =- Explanation: Basic Concepts: Magnetic Force on a Charged Particle: ~ F = q~v ~ B Right-hand rule for cross-products. The force is given by ~ F = q~v ~ B . ~ B = B - k ~v = v (+ ) q > Therefore ~ F = q~v ~ B = q v B h (+ ) - k i = q v B (+ ) . 002 (part 2 of 2) 10 points A positively charged particle enters a mag- netic field, as shown in the figure below. What is the initial direction of deflection? B 45 k j i + ^ ^ ^ 1. F = + 2. F =- 3. F =- 4. k ~ F k = 0, no deflection 5. F = + k 6. F =- k correct 7. F = + Explanation: ~ B = B 2 [(+ ) + (+ )] ~v = v (+ ) q > Therefore ~ F = q~v ~ B = q v B 2 (+ ) [(+ ) + (+ )] = q v B 2 - k . 003 (part 1 of 1) 0 points Given: A long straight wire and a wire loop in the same plane. The long wire has a current flowing in the direction shown. The wire loop is moving in the direction shown. Arb, Kellen Homework 15 Due: Oct 6 2004, 4:00 am Inst: Turner 2 I v wire loop wire straight The current in the loop is flowing 1. There is no current in the loop. 2. clockwise. correct 3. counter-clockwise. Explanation: Using the right hand rule, in the fol- lowing figure, and taking into considera- tion the direction of the magnetic field, we find that the direction of the current flow- ing in the loop is as shown in the figure. I v i B 004 (part 1 of 4) 0 points Consider two long parallel wires which are perpendicular to the plane of the paper ( i.e. , the x- y plane. See figure). Both wires carry the same current, I . Wire #1 intersects the plane a distance a above point O and wire #2 intersects the plane a distance a below point O . Point C is equidistant from both wires and is a distance a from point O . a a a a O C D wire #2 wire #1 45 45 x y I II III IV O The direction of the magnetic field at C is 1. out of the plane. 2. in quadrant I. 3. in quadrant IV. 4. in the positive y direction. 5. in the positive x direction. correct 6. in quadrant III....
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- Spring '08