Introduction
State vectors
Stern Gerlach experiment
S
N
B
zÙ
o v e n
c o l l i m a t o r
t o d e t e c t o r
In the Stern Gerlach experiment
• silver atoms are heated in an oven, from which they
escape through a narrow slit,
• the atoms pass through a collimator and enter an
inhomogenous magnetic field, we assume the field to
be uniform in the xy-plane and to vary in the
z-direction,
• a detector measures the intensity of the electrons
emerging from the magnetic field as a function of z.
We know that
• 46 of the 47 electrons of a silver atom form a
spherically symmetric shell and the angular
momentum of the electron outside the shell is zero,
so the magnetic moment due to the orbital motion of
the electrons is zero,
• the magnetic moment of an electron is cS, where S
is the spin of an electron,
• the spins of electrons cancel pairwise,
• thus the magnetic moment µ of an silver atom is
almost solely due to the spin of a single electron, i.e.
µ = cS,
• the
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