A particle of mass 0.390 g carries a charge of 2.00 x10^-8 C. The particle is given an initial horizontal velocity that is due west and has a magnitude 7.00 x 10^4 m/s. What are the magnitude and direction of the minimum magnetic field that will keep the particle moving in the earth's gravitational field in the same horizontal, westward direction? Magnitude T Direction northward eastward westward southward