I'm confused if I am using the right equations to solve this problem. P: A singly charged Li^7 ion has a mass of 1.16x10^-26kg. It is accelerated through a potential difference of 500 Volts and then enters a magnetic field of 0.4 Teslas, moving perpendicular to the field. What is the radius of its path in the magnetic field. I had two different solutions to this problem that has to completely different answers. First, I figured I can use the equation V=(kq)/r. Then I solved for the radius. The second way is by using the volts equation: V=PE/q, which I use to solve for the potential energy. I then used this in the kinetic energy equation KE=1/2mv^2 to solve for the velocity. This velocity I then used in the equation r=(mV)/(Bq). I got 2.88x10^-12 meters for the first solution and 3.44x10^13 meters for the second solution. Which one is right is any?