1. The problem statement, all variables and given/known data A 7.00-cm-long wire is pulled along a U-shaped conducting rail in a perpendicular magnetic field. The total resistance of the wire and rail is 0.320Ω . Pulling the wire with a force of 1.30N causes 4.50W of power to be dissipated in the circuit. What is the speed of the wire when pulled with 1.30N ? What is the strength of the magnetic field? 2. Relevant equations ε=vBL P=Fv I=ε/R I=sqrt(P/R) 3. The attempt at a solution I=sqrt(P/R) I=sqrt(4.5/0.32)=3.75 amps I=ε/R 3.75 amps = ε/0.32 ε=1.2 V ε=vBL (1.2 V)=v(???)(0.07 m) I'm not sure how to find the magnetic field, which I obviously need for both parts. Please help! Thanks!