‘
398
17.
SMALL CURRENT TECHNIQUE
Figure 17—12 shows the idiostatic connection for measuring
the voltage v. Here the needle and one of the quadrants are
___
raised
to
the same potential
P
(With respect to the other quad—
' _
rant Q'). The applied voltage
-Î
may
be either alternating or di—
Î'
rect in this case since the needle
is
attracted
(rotated) in the
@
Q
same direction whether it is pos' __
fi
itive and the free quadrant Q’
negative or vice versa. It is to
"
be noted that the instrument
does not use any current when
operated in the heterostatic or
.
'
V
idiostatic manner.
F1G. 17—12.
voltage con—
E‘1gure
ShO_WS
the
nection of an electrometer.
nect1on
for measuring a small
current
passing between the
plates  and B by the so-called rate of d€ectian method. Charges
of electricity formed in the gas between  and B (by et radio—
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platethheacceleratmgpotenüalv …AS the chargebuds