DOC.
564
JUNE
1918 587
acting
on
the
charges
in G divided
by
the
size of
the domain itself
yields
the
force
density
BF^V
B B (
1
r
ï
M"
-
Ö?{«5/
1) 2) 3)
1)
stems from
the
true current in domain
G,
2)
from
the
polarization current
and
3)
is
the
force exerted
by
all
molecules
attached
to
the
exterior of domain G
and
cut
by
the
surface of
G.
That
means,
all
the
countless
rubberbands
cut
by
a
surface element have
as a resulting
tension
a simple pull
perpendicular
to
the
element, regardless
of
how this element
may
be
orientated,
of
the
quantity
1/2
/
MaßdFaß.
Since
we are
just
considering isotropic,
nondis-
persing,
hysteresis-free media,
each
comp[onent]
Maß
depends only upon
its
corresponding
Faß.
The
integral
should be extended from
zero
po-
larization until the
actually existing
value. The
known
rewriting
of term
(1)
with
the
induction
law
yields
Ka =
dTav/dxv
where
the
energy-momentum
tensor
is
Tva
=
-Faa{Fva
-
MVOt)
+ K~J
(Faß
~
Maß)dFaß
or
let Daß
=
Faß
-
Maß be
the
tensor
“displacement”
with
the
comp.
{h, d}.
r;
=
-FaaD™ +
U:
I
DaßdFaß
Field
&
matter
can
be held
strictly apart.
Of
more
interest
is
Tva
in
comp.
upon
amalgamation
according to[5]
Tva
=
exÖx
+
ï)xbx
-
ƒ
(öde
+
bdt)) txby
+
l)xb,,
ex0*
+
t]xbz
H
,/cT.
1
*yÔÿ
+
fyyby
'(öde
+
bdt])
“t~
fyybz
-[ö,
b]"
“t”
fyz^x
tz^y
“f“ fyz^y
e*ö*
+
&*b*
-/(öde
+
bdïj)
-[ö,
b\z
[e, Wx
[*
W» [e,
%
J{tdb
+
]db)