A proton moves in a circular path perpendicular to a 4.30 T. magnetic field. The radius of its path is 7.5 cm. Calculate the energy of the proton in electron-volts. I'm not sure which equation to use. I tried using m=rqB/v and found the velocity. However, I'm not sure how to relate that to energy. Mass of proton equals 1.67E-27. Q of proton = 1.6E-19. 1eV=1.6E-19 J.