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Unformatted text preview: fryer (vdf96) Magnetics graves (6) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points An electron is in a uniform magnetic field B that is directed out of the plane of the page, as shown. v e- B B B B When the electron is moving in the plane of the page in the direction indicated by the arrow, the force on the electron is directed 1. toward the top of the page. correct 2. out of the page. 3. toward the left 4. toward the bottom of the page. 5. toward the right 6. into the page. Explanation: The force on the electron is vector F = q vectorv vector B =- e vectorv vector B. The direction of the force is thus hatwide F =- hatwide v hatwide B , pointing toward the top of the page , using right hand rule for hatwide v hatwide B , and reversing the direction due to the negative charge on the electron. 002 10.0 points A particle with charge q and mass m is un- dergoing circular motion with speed v . At t = 0, the particle is moving along the nega- tive x axis in the plane perpendicular to the magnetic field vector B , which points in the positive z direction in the figure below. x y z vectorv vector B Find the direction of the instantaneous ac- celeration hatwide a at t = 0 if q is negative. 1. hatwide a =- k 2. hatwide a =- j correct 3. hatwide a =- k + i 4. hatwide a =- i 5. hatwide a = j 6. hatwide a = i + j 7. hatwide a = k + i 8. hatwide a = k 9. hatwide a = j + k 10. hatwide a = i Explanation: The particle is moving along the negative x-axis in this instant vectorv =- v i ; since it is moving in a circle, we need to talk about instantaneous direction....
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This note was uploaded on 12/11/2011 for the course PHYSICS 101 taught by Professor Graves during the Fall '10 term at San Jose City College.
- Fall '10