1. The problem statement, all variables and given/known data A proton orbits a long charged wire, making 1.30*10^6 revolutions per second. The radius of the orbit is 1.20cm. What is the wire's linear charge density? 2. Relevant equations - q E = m w^2 r - 9*10^9 [2 λ /r] q = m w^2 r 3. The attempt at a solution λ = linear charge dens w = 2pi/period = 2pi/T w = d theta/dt = 1.4* 2pi /1 I'm confused on how to solve for λ here though. Can anyone help me out?