At a point high in the Earths atmosphere, He 2+ ions in a concentration of 2.8 X

Question:

At a point high in the Earth’s atmosphere, He 2+ ions in a concentration of 2.8 X 1012/m3 are moving due north at a speed of 2.0 X 105 m/s. Also, a 7.0 X 1011/m3 concentration of O2 ions is moving due south at a speed of 7.2 X 106 m/s. Determine the magnitude and direction of the net current passing through unit area (A/m2).