1. The problem statement, all variables and given/known data Find the magnetic field at position z (z=0 in the plane of the ring) along the rotation axis for a circular ring of radius r, carrying a uniform linear charge density λ, and rotating about its axis with angular velocity ω. 2. Relevant equations I=q/t ω=2πf f=1/period Biot-Savart Law 3. The attempt at a solution I can determine the magnetic field when the ring is just a current loop that is not rotating. Once the rotation comes into play I get really confused about how to handle the linear charge density λ and the angular velocity. I see that I can solve for time in the equation for current (I=q/t) and end up with: I=(qω)/(2π) I think λ=charge/length but should it instead be: λ=dq/dl?