Hi All, Having difficultly figuring out where I've gone wrong with this problem. Any guidance gratefully received. 1. The problem statement, all variables and given/known data A 4.76 keV electron (an electron that has a kinetic energy equal to 4.76 keV) moves in a circular orbit that is perpendicular to a magnetic field of 0.392 T. i) Find the radius of the orbit. 2. Relevant equations KE = 0.5 m v^2 r = mv / qB (where r = radius, m = mass of electron, q = charge of electron and B = magnetic field) 3. The attempt at a solution Given the KE and the mass, find the velocity v. KE = 4.76 x 10^3 eV and m = 9.109x10^-31 kg v = sqrt ( (2xKE / m)) v = sqrt ( (2x(4.76x10^3)/9.109 x 10^-31)) v= 1.02 x 10^17 m/s Now having found the velocity v, find the radius r. r = mv / qB r = (9.109x10^-31)(1.02 x 10^17) / (1.602x10^-19)(0.392) r = 1.48 x 10^6 m However this answer is wrong and I don't know where I'm going wrong. Any help greatfully recieved.