DOC.
47 281
generating
potential
or
the kinetic
energy
of the
rays,
the
deflectability
by
an
electric
field,
and
the
deflectability
by
a
magnetic
field.
According
to (14),
the
generating potential
II
is
given
by
the formula
IIe
-
//
-1
[50]
To
calculate the
two
other quantities,
we use
the last of
equations
(11)
for
the
case
when
the
motion
is
momentarily
parallel
to
the
X-axis;
denoting
the
absolute value of the
electron's
charge
by e,
one
obtains
d2z
4
Z
+
^
M 1
p'
c2
c
If
Z
and
M
are
the
only
deflecting
field
components,
and hence
the
bending
takes
place
in
the
XZ-plane,
the radius of
curvature
R
of the
trajectory is
given
by
jR{~
=
q2
d2z
dt2.
Hence,
if
the
electric
and
magnetic
deflectability
are
1
1
defined
as
the
quantities
Ae =
R
:
Z and
Am
=
R
:
M
respectively
for the
case
that
only
one
deflecting electric
or
only
one
magnetic
field
component
is
present,
one
has
1
-
4c1
I*
"2
i
~
€cz
J
=
i
m
\i cq
In
the
case
of cathode
rays
all three
quantities
II,
Ae,
and
A
are
possible candidates for
measurement; however,
no
investigations with
sufficiently fast cathode
rays
have
yet
been
performed.
In the
case
of
/?-rays, only
the
quantities
A
and
A
are
(in practice) accessible
to
e
m
observation.
Mr.
W.
Kaufmann
ascertained the relation
between
A
and
Ae
m
for
/?-rays
emitted
by a
radium bromide
granule
with admirable
care.1
[51]
1W.
Kaufmann,
"Über
die Konstitution
des
Elektrons"
[On
the constitution of
the
electron].
Ann.
d.
Phys.
19 (1906). Both
figures
are
taken
from
Kaufmann's
paper.
[52]