1. The problem statement, all variables and given/known data A thin, non-conducting ring of mass m, carrying a charge q, can rotate freely about the axis. At the instant t=0 the ring was at rest and no magnetic field was present. Then suddely a magnetic field B was set perpendicular to the plane. Find the angular velocity acquired by the ring. 3. The attempt at a solution Before proceeding towards attempt at the solution, I would like to find out why will the ring start rotating? The ring is non-conducting, so there should not be any induced current. Which essentially means that there is no current flow even if there is an induced electric field. I don't get this part.