1. The problem statement, all variables and given/known data The question is based on the Bohr model with an electron with charge e and mass m orbiting a proton about a circular radius r. I have to find k in the equation I = e2 / sqrt kε0r3m where k is a some combination of constants. 2. Relevant equations Coulumb's force law: F = kq1q2/r2 Centripetal force: mω2r Current: I = q/t k = 1/4πε0 3. The attempt at a solution I equated columb's force law to the centripetal force to give mω2r = ke2/r2 Then rearranged to get ω2 = ke2/mr3 Then I changed ω for 2π/T and square rooted both sides to give 2π/T = ke2/mr3 From here I'm just not sure how to get it into the form of the equation asked for.