Radio-Activity

by Ernest Rutherford

dr = Xu₂ dt,

or

Let r₂ be the greatest distance measured from the axis of the tube from which the negative ion can just reach the electrode A in the time t taken for the air to pass along the electrode.

Then

If ρ₂ be the ratio of the number of the negative ions that reach the electrode A to the total number passing by, then

Therefore