Question

Group Name: Individual Name: PHYSICS 200: ELECTRICITY AND MAGNETISM CHAPTER 27 GROUP WORK: MAGNETIC FIELDS (MONDAY) CONCEPT Can a charged particle move through a magnetic field without experiencing any force? If so, how? If not, why not? PROBLEM Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. These cyclotrons typically accelerate H-(the hydride ion, which has one proton and two electrons) to an energy of 5 MeV to 20 MeV. This ion has a mass very close to that of a proton because the electron mass is negligible-about 1/2000 of the proton's mass. A typical magnetic field in such cyclotrons is 1.9 T. (a) What is the speed of a 5.0-MeV H-? (b) If the H-has energy 5.0 MeV and B = 1.9 T, what is the radius of this ion's circular orbit:

Answer 1

Concept: If the velocity of the charged particle is either parallel or anti-parallel to the direction of magnetic field the particle will experience no force. Problem: a. Speed of Hion 2E Speed of the ion v= = Ym 2x 5 x10x1.6x10-19 V 1.6x10-27 = 3.16x10 m/s b. Radius of Orbit (Mass of electron is neglected) R = my q = Charge of Hion = e 1.6x10-27x3.16x107 1.6x10-19 x1.9 = 16.6 cm