The accurate experiments of Chattock and Bates prove that the angular momentum arising in a ferromagnetic substance from unit change in its magnetic moment is very nearly, if not exactly, one half the value 2
m/e
= 1.13 X 10
-7
, which seemed to me the most likely when I first discussed this effect. This conclusion is supported by the fact that the improvements which have been introduced into this subject by successive experimenters in recent years have led to values showing a strong tendency to settle at the same limit
m/e
= 5.65 X 10
-8
. This value is also in general agreement with that deduced by Barnett from experiments on the converse effect. It seems desirable therefore to reconsider the interpretation of this ratio. The higher value 2
m/e
is obtained by making rather definite assumptions, which evidently require modification, as to the nature of the phenomena. These assumptions are that the process of magnetization involves the turning of electron orbits, and that nothing else which may occur has any important influence on the phenomena. The inertia of the electrons is assumed to be entirely of the type which controls the deflection of a beam of cathode rays by a magnetic field, and any change in the motion of the positively charged part of the atom is disregarded. These assumptions are essentially the same as those of the theories of Langevin and Weiss which have been successful in dealing with purely magnetic phenomena.
Control of the RF magnetic field pattern by tunable metasurface in 1.5 T MRI
