DOC.
11
LECTURE ON ELECTRICITY
&
MAGNETISM
323
_d_^
ac,
sc.
c
dt
\
dz
J
dx
\
dx
dy
dz
v
y
'
c
dt
lisd2(&x
-2 -5-5
AG
=
0.
etc
dt
These
are
the
fundamental
equations
of
the
wave theory.
The
Energy Principle
and
the Law of Conservation
of
Momentum
n
dbx
_
d&2
d%y
c&.
c
dt
dy
dz
47t
H d§y
_
dSx
d£z
£y
-
c--
c
dt dz
dx
\
/
47T
47t
ß
d§z
_
d(!£y
^3dx
c.&
c
dt
dx
dy
4n
471
*1
4rc
§
+
««.A
+ +
•)--£
-
«JW
+
•
+
Is canceled
by
what
comes
from the
right-hand
side
of the
second
system.
.
c
d
^ ,
,
c
(K
d%z
K
d%y\
47t
~
y)
+
47t
V
y dx
dx
)
Sx
Sy
Sz
+ AG
8
0SX
d£z
c
dt
dy
dz
4n
ed£y
1
CD
&X
%
C
c
dt
dz
dx
/
/
4
n
ed(£z
c
dt
11
8-#\
V
'
d%x
dy
c*
4n
[75]
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