314
MEASUREMENT OF SMALL CHARGES
T
T
%
Fig. 2
r2
h
n
=
A-«1
^2'
fl2
-
/,1-a1-a2
P'
-
r2
-
^3
~
^3'fl3
-
'rfll,fl2,fl3'
If
there
are n
elements, all
of them
with the
same
transmission
ratio
a,
then
we
will
have
rn
=
P1an
.
One can see
that the
energy
that
has
to be
supplied
to
the
mobile
system
of
the electrometer is taken
from
the
mechanical
energy
imparted to
the
leaflets
B,
and not
from
the
system
to be measured,
which
is connected
to
the
leaflet
A.
The
sensitivity
of
the
procedure
is limited
only
by
the
external
sources
of
error,
since
an
can
be
made
arbitrarily
large
by
increasing
n.
Of
course,
the
whole
arrangement
can
be
made
to be
bipolar. In that
case
each element gets
two primary and two
secondary
conductors.
[4]