1. The problem statement, all variables and given/known data A magnetic field of 0.1 T forces a proton beam of 1.5 mA to move in a circle of radius 0.1 m. The plane of the circle is perpendicular to the magnetic field. Of the following, which is the best estimate of the work W done by the magnetic field on the protons during one complete orbit of the circle? 1. W = 0 J 2. W = 10^22 J 3. W = 10^−22 J 4. W = 10^20 J 5. W = 10^−5 J 2. Relevant equations F = qVB = ILB F = mv^2 / r C = 2 pi*r 3. The attempt at a solution Since work is energy, I used the formula for kinetic energy... W = 1/2 mv^2 Fcentripetal = Fmagnetic mv^2 /r = qvB v = rqB / m W = 1/2 m (rqB / m)^2 W = 1/2 (1.6725 x 10^-27) * (0.1 * 1.602 x 10^-19 * 0.1 / 1.6725 x 10^-27) ^2 W = 7.67235874 x 10^-16 J This isn't close to any of the answer choices. Can someone help me?