A 2.3-m-long wire carries a current of 8.1 A and is immersed within a uniform magnetic field B. When this wire lies along the +x axis [i.e., the current is directed in the +x direction], a magnetic force F = - 2.4j N acts on the wire, and when it lies along the +y axis [i.e., the current is directed in the +y direction], the force is F = (2.4i - 4.9k) N. Find B.