Two Long Parallel Wires Carry Unequal Currents in the Same

Multiple Choice

Two long parallel wires carry unequal currents in the same direction. The ratio of the currents is 3 to 1. The magnitude of the magnetic field at a point in the plane of the wires and 10 cm from each wire is 4.0 μT. What is the larger of the two currents?

A) 5.3 A
B) 3.8 A
C) 4.5 A
D) 3.0 A
E) 0.5 A