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 V/m and the field is directed vertically down. This field causes singly charged positive ions, at a density of `640 cm^(-1)` to drift downward and singly charged negative ions, at a density of 550 cm`""^(-3)`. ? to drift upward (Fig. 26-20). The measured conductivity of the air in that region is `2.70 xx 10^(-14)W (Omega.m)^(-1)`. Calculate (a) the magnitude of the current densily and (b) the ion drift speed, assumed to be the same for positive and negative ions.

Answer

`(a) 3.24 xx 10^(-12) A//m^(2); (b) 1.70 cm//s`