Review Conceptual Example 2 as an aid in understanding this problem. The drawing shows a positively charged particle entering a 0.73-T magnetic field. The particle has a speed of 200 m/s and moves perpendicular to the magnetic field. Just as the particle enters the magnetic field, an electric field is turned on. What must be the magnitude of the electric field such that the net force on the particle is twice the magnetic force? Number Units V