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Unformatted text preview: wilson (kw22588) HW9 Mackie (20224) 1 This printout should have 15 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 3) 10.0 points The magnetic field over a certain range is given by vector B = B x + B y , where B x = 8 T and B y = 5 T. An electron moves into the field with a velocity vectorv = v x + v y + v z k , where v x = 4 m / s, v y = 8 m / s and v z = 4 m / s. The charge on the electron is 1 . 602 10 19 C. What is the component of the force ex erted on the electron by the magnetic field? Correct answer: 3 . 204 10 18 N. Explanation: Let : v x = 4 m / s , v y = 8 m / s , v z = 4 m / s , q = 1 . 602 10 19 C , B x = 8 T , and B y = 5 T . The force exerted on the electron by the mag netic field is given by vector F = qvectorv vector B = q vextendsingle vextendsingle vextendsingle vextendsingle vextendsingle vextendsingle k v x v y v z B x B y vextendsingle vextendsingle vextendsingle vextendsingle vextendsingle vextendsingle = q [ v z B y + v z B x + ( v x B y v y B x ) k ] = ( 1 . 602 10 19 C) { (4 m / s) (5 T) + (4 m / s) (8 T) + [(4 m / s) (5 T) (8 m / s) (8 T)] k } = (3 . 204 10 18 N) + ( 5 . 1264 10 18 N) + (7 . 0488 10 18 N) k 002 (part 2 of 3) 10.0 points What is the component of the force? Correct answer: 5 . 1264 10 18 N. Explanation: See the above part. 003 (part 3 of 3) 10.0 points What is the k component of the force? Correct answer: 7 . 0488 10 18 N. Explanation: See the above part. 004 (part 1 of 2) 10.0 points An electron in an electron beam experiences a downward force of 3 . 10 14 N while trav eling in a magnetic field of 4 . 1 10 2 T west. The charge on a proton is 1.60 10 19 . a) What is the magnitude of the velocity? Correct answer: 4 . 57317 10 6 m / s. Explanation: Let : F m = 3 . 10 14 N , B = 4 . 1 10 2 T , and q e = 1 . 60 10 19 C . The magnetic force is F m = q v B v = F m q B = 3 10 14 N (1 . 6 10 19 C) (0 . 041 T) = 4 . 57317 10 6 m / s 005 (part 2 of 2) 10.0 points b) What is its direction? 1. East 2. None of these 3. West 4. North correct wilson (kw22588) HW9 Mackie (20224) 2 5. South Explanation: Apply righthand rule (for a negative charge); force directed into the palm of the hand, fingers in the direction of the field, thumb in the direction of the velocity....
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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

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