Earth's lower atmosphere contains negative and positive ions that are produced by radioactive elements in the soil and cosmic rays from space. In a certain region, the atmospheric electric field strength is 120 Y lm and the field is directed vertically down. This field causes singly charged positive ions, at a density of 620 cm-3, to drift downward and singly charged negative ions, at a density of 550 cm-3, to drift upward (Figure). The measured conductivity of the air in that region is 2.70 x 10-14 (?? ?? m)-1. Calculate

(a) The magnitude of the current density and

(b) The ion drifts speed, assumed to be the same for positive and negative ions.