A sodium ion with mass 2.32×10-26 kg and charge +1.60×10-19 C is moving with velocity 3.00×105 m/s in the positive x direction. An identical particle is moving with the same speed in the negative x direction, but displaced by +1.50 m in the y direction. When the x coordinates of the atoms are equal, a magnetic field perpendicular to their motion is turned on so that the atoms collide head-on. What are (a) the magnitude and (b) the direction of the magnetic field?