Chapter 27, Problem 27.80P

DATA You are a technician testing the operation of a cyclotron. An alpha particle in the device moves in a circular path in a magnetic field $\stackrel{\to }{\text{B}}$ that is directed perpendicular to the path of the alpha particle. You measure the number of revolutions per second (the frequency f) of the alpha particle as a function of the magnetic field strength B. Figure F27.80 shows your results and the best straight-line fit to your data, (a) Use the graph in Fig. P27.80 to calculate the charge-to-mass ratio of the alpha particle, which has charge +2e. On the basis of your data, what is the mass of an alpha particle? (b) With B = 0.300 T. what are the cyclotron frequencies f of a proton and of an electron? How do these f values compare to the frequency of an alpha particle? (c) With B = 0.300 T, what speed and kinetic energy does an alpha particle have if the radius of its path is 12.0 cm?

Figure F27.80