1. The problem statement, all variables and given/known data I'm answering a question which describes a situation in which a metal ring is dropped through a magnetic field such that, when it falls, its area is perpendicular to the magnetic field. I need to find its terminal velocity given: Mass : 2.66 x 10-4 kg Magnetic flux density : 2.00 T Radius : 2.00 cm Resistance : 2.48 m(ohms) 2. Relevant equations Emf = dBA/dt V = IR F = BILsin(theta) 3. The attempt at a solution At terminal velocity, the magnetic force as a result of the ring's current must equal its weight: mg = BIL I'm confused about how to introduce v into the equation E.m.f = dBA/dt. My thoughts were as follows: If A is the area through which the ring moves in time dt then A = pi r2vdt e.m.f = (dBpi r2vdt)/dt e.m.f = dBpi r2v Dividing both sides by R : I = (dBpi r2)/ R I would then set this equal to mg / BL to find v. However, in previous questions 'L' has always been a straight wire. Would you use the diameter of this metal ring or its circumference? My feeling is the circumference but I'm not 100% sure. Also, is the way I've approached this question right?