--- x1 ---- qT
2 x2
The remainder of the carriers, produced between A and B during a complete alternation, will reach the other plate A in the course of succeeding alternations, provided no appreciable recombination takes place. This must obviously be the case, since the positive carriers travel further in a half alternation towards A than they return towards B during the next half alternation. The carriers thus move backwards and forwards in the changing electric field, but on the whole move towards the plate A.
The total number of positive carriers produced between the plates during a complete alternation is 2dqT. The ratio ρ of the number which reach B to the total number produced is thus given by
Substituting the values of x1 and x2, we find that
In the experiments, the values of E₀, E1, d, and T were varied, and the results obtained were in general agreement with the above equation.
The following were the results for thorium:
Plates 1·30 cms. apart.