Introduction
When
: There is no interaction between the field
and
(they are not in accord) and the precession is kept around the axis Oz.
When
:
and
are in accordance. Thus the couple applied by
modifies the angle
of
with 0z, and then causes transitions between the magnetic sublevels.
There is resonance. The value of the z magnetization decreases and it appears, in the y direction, the transverse magnetization My.
