1. The problem statement, all variables and given/known data The force on a wire .80 m long that is perpendicular to the Earth's magnetic field is .12 N. What current flows throught the wire? (Earth's magnetic field is 1.0x10^-4 T at the poles and 5.0x10^-5 T at the equator) 2. Relevant equations Fm=BIl Fm is magnetic force in N, B is magnetic field strength in telsa (T), and l is length in meters. 3. The attempt at a solution I'm just not sure what I'm supposed to use for B. Do I use the strength at the poles? at the equator? Some combination of the two? Thanks.