140 DOC.
28
SIMPLE EXPERIMENT
[p. 176]
when
brought
from underneath with
a
finger.
The
droplet
melts and
curves
under the
action
of
capillary
forces into
a
very symmetric bulge.
If
one now brings
the thread
of
quartz
into contact with the
colophony,
the
capillary
forces will suck it into the
droplet as
deeply
as possible,
thus
centering
it
automatically.
After
cooling,
the
suspension
is finished. After
this, one can use
wax
to fasten the little mirror
(3 mm2
and made from
a
microscope slide)
onto the
tiny
rod.
It should also be
pointed
out that the effect
to
be demonstrated cannot be
confused with the
purely magnetically
induced
angular
momenta
of
the
tiny
rod,
which will be
present
due to the combination of nonvertical
positioning
and
asymmetry
of
the
coil's fields with the
asymmetries
in the
tiny
rod. The
reason
is
that
every
commutation
changes
both the field and the
magnetic poles
in
sign,
relative to
the
previous
state,
so
that the
resulting angular
momentum has the
same sign
in both
cases
and
thus
cannot
cause a
systematic
amplification or
attenuation
of
the
oscillations.
By
the
way,
if
such
angular
momenta become
noticeable,
they can easily
be eliminated
by adjusting
of
the
balancing
screws.
Finally one more point which, originally, gave me some
headaches. The effect
demanded
by
the
theory
is
large enough
to be demonstrated when the
tiny
rod is
stimulated from its
resting position by just one single
commutation. The
experiment,
however,
always produced
in this
case only
a
rather fast vibration
of
the
tiny rod,
without
a
noticeable torsional oscillation.
A
simple analysis
shows that this
originates
with the eccentric
suspension
of
the
tiny
rod. The
reason
being
that,
about
(almost)
the main axis
of
inertia, a
torsional oscillation is initiated whose
directional force
does
not
come
from the torsion
of
the
thread,
but rather from the
weight
of
the
tiny
rod.2
[p.
177]
Here I
want to
express my
sincerest thanks
to
my colleagues
Jaeger
and
[4]
Orlich, the first-named for his kind
assistance,
the other for
producing
the
special
coil,
mentioned above. The
experiment was
first conducted with the kind
permission
[5]
of
Herr
Warburg
at the Reichsanstalt.
2This kind
of
oscillation
can
be
easily
observed
on an elongated,
not too slender
body
when
it
is in
asymmetric suspension, e.g.,
like
a larger pair
of
scissors
hanging
by
a
thread
from
one
of
its
grip
holes.
If
this hole is
given
a slight
push at
the
point
of
suspension,
and
perpendicular
to
the
plane
of
the
edges,
the motion mentioned above sets in.
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