DOC.
47 267
1

cosy
V
(4a)
The
last
two equations express
Doppler's
principle in its
general
form;
the last
equation shows
how
the observable
frequency
of
the light emitted
(or
absorbed)
by
canal
rays
depends
on
the velocity of
motion
of
the
ions that
form
the
rays
and
on
the direction of
sighting.
If
the
angles
between
the
wave
normal
(ray
direction)
and
the direction
[32]
of
relative
motion
of S'
with
respect to
S
(i.e., with the
x
and
x'axis,
respectively)
are
called
Q
and Q', respectively,
the
equation
for
l' takes the
form
cos
cos
(fi
p
 
cos
ip
1

COS
(p^
This
equation shows
the effect
of
the relative
motion
of the observer
on
the
apparent
location of
an
infinitely
distant
source
of
light (aberration).
In
addition
we
will also examine
how
fast
light
is
propagated
in
a
medium
that is
moving
in the direction of the light
ray.
Let
the
medium
be
at
rest
relative
to
the
system
S',
and
let the light
vector
be proportional
to
or
to
sin
w
t
 V ,
respectively,
depending
on
whether
the
process
is
referred
to S'
or
S.
The
transformation
equations
yield
o) =
1 +
Y