An electron in a uniform magnetic field B has a velocity & = 4.0\times 105 i( m)/(s) + 7.1x105( m)/(s). It experiences a magnetic force F = -2.7x10-13 Î N + 1.5x10-13 f N. If Bx = 0, the compo- nents By and By (with sign included and in units of Tesla) of the magnetic field are closest