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Unformatted text preview: Patel, Kinal Homework 11 Due: Feb 29 2008, 7:00 pm Inst: Weathers 1 This print-out should have 12 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 1) 10 points A positively charged particle moving paral- lel to the y-axis enters a magnetic field (point- ing toward the bottom of the page), as shown in the figure below. y z v x ~ B ~ B + q Figure: is in the x-direction, is in the y-direction, and k is in the z-direction. What is the initial direction of deflection? 1. b F = + k 2. b F =- k 3. b F = + correct 4. b F = + 5. b F =- 6. b F =- 7. ~ F = 0 ; no deflection Explanation: Basic Concepts: Magnetic Force on a Charged Particle: ~ F = q~v ~ B Right-hand rule for cross-products. b F ~ F k ~ F k ; i.e. , a unit vector in the F direc- tion. Solution: The force is ~ F = q~v ~ B . ~ B = B - k , ~v = v (- ) , and q > , therefore , ~ F = + | q | ~v ~ B = + | q | v B h (- ) - k i = + | q | v B (+ ) b F = + . This is the fifth of eight versions of the problem. keywords: 002 (part 1 of 1) 10 points A proton moving at 5 . 9 10 6 m / s through a magnetic field of 3 . 1 T experiences a magnetic force of magnitude 2 10- 12 N. The charge of proton is 1 . 60218 10- 19 C and the mass of proton is 1 . 67262 10- 27 kg. What is the angle between the protons velocity and the field? Correct answer: 43 . 0397 . Explanation: Let : E = 2 10- 12 N , B = 3 . 1 T , v = 5 . 9 10 6 m / s , q p = 1 . 60218 10- 19 C , and m p = 1 . 67262 10- 27 kg . The Lorentz force acting on a moving charged particle in a magnetic field is F = q v B sin , where q is the charge, v is the speed, B is the magnetic field. So thus the angle between the velocity and the field is = arcsin F q v B = arcsin (2 10- 12 N) (1 . 60218 10- 19 C) 1 (5 . 9 10 6 m / s) (3 . 1 T) = 43 . 0397 . Patel, Kinal Homework 11 Due: Feb 29 2008, 7:00 pm Inst: Weathers 2 keywords: 003 (part 1 of 3) 10 points The magnetic field over a certain range is given by ~...
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This note was uploaded on 10/24/2010 for the course PHYS PHYS 2220 taught by Professor Weathers during the Spring '08 term at North Texas.
- Spring '08