If the electricity carried by the electron is supposed to be distributed uniformly over a sphere of radius a, for speeds slow compared with the velocity of light, the apparent mass m_{0} = (2/3)(e^2/a).
Therefore a = (2/3)(e/m_{0}) . e.
Taking the value of e as 1·13 × 10^{-20}, a is 1·4 × 10^{-13} cms.
Thus the diameter of an electron is minute compared with the diameter of an atom.
83. Distribution of velocity amongst the β particles.
Some interesting experiments have been recently made by Paschen[1]
to determine the relative number of β particles which are expelled
from radium at the different speeds. The experimental arrangement
is shown in Fig. 29.
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Fig. 29.
A small thin silvered glass tube b, containing 15 mgrs. of radium bromide, was placed in the axis of a number of lead vanes arranged round a cylinder of diameter 2 cms. and length 2·2 cms.
- ↑ Paschen, Annal. d. Phys. 14, p. 389, 1904.
