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Unformatted text preview: Nguyen, Thanh Homework 12 Due: Mar 4 2008, 7:00 pm Inst: Weathers 1 This printout should have 10 questions. Multiplechoice 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 What is the radius of the smallest possible circular orbit that a 3 . 7 MeV proton can have in a 3 T magnetic field? The mass of a proton is 1 . 67 10 27 kg and its charge is 1 . 609 10 19 C. Correct answer: 0 . 0923793 m. Explanation: Let : m = 1 . 67 10 27 kg , Q = 1 . 609 10 19 C , B = 3 T , and E = 3 . 7 MeV . The energy of a proton is E = 1 2 m v 2 , so v = r 2 E m = s 2 (3 . 7 MeV) (1 . 609 10 19 J / eV) (1 10 6 MeV / eV) (1 . 67 10 27 kg) = 2 . 67015 10 7 m / s . If the proton is shot into the magnetic field with a velocity at right angles to the direction of the field, we will get the smallest radius r = m v B q = (1 . 67 10 27 kg) (2 . 67015 10 7 m / s) (3 T) (1 . 609 10 19 C) = . 0923793 m . keywords: 002 (part 1 of 1) 10 points A singlycharged positive ion has a mass of 1 . 2 10 26 kg. After being accelerated through a potential difference of 756 V, the ion enters a magnetic field of 0 . 897 T along a direction perpendicular to the direction of the electric field. The charge on an electron is 1 . 60218 10 19 C. Calculate the radius of the path of the ion in the magnetic field. Correct answer: 0 . 0118637 m. Explanation: Let : m = 1 . 2 10 26 kg , B = 0 . 897 T , V = 142082 m / s , and q = 1 . 60218 10 19 C . Energy conservation: 1 2 m v 2 = q U so the speed of the ion is: v = r 2 q U m = s 2 (1 . 60218 10 19 C) (756 V) 1 . 2 10 26 kg = 142082 m / s The magnetic force provides the centripetal force: q v B = m v 2 r r = m v q B = (1 . 2 10 26 kg) (142082 m / s) (1 . 60218 10 19 C) (0 . 897 T) = . 0118637 m . keywords: 003 (part 1 of 2) 10 points A cyclotron with a magnetic field of 0 . 47 T is designed to accelerate protons in a circle with a radius 1 . 3 m. Nguyen, Thanh Homework 12 Due: Mar 4 2008, 7:00 pm Inst: Weathers 2 What is the angular frequency of the pro ton?...
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This note was uploaded on 10/24/2011 for the course PHYS 2220 taught by Professor Littler during the Spring '00 term at North Texas.
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