_
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17—7.
CALIBRATION OF AN ELECTROSCOPE 39(5
cylinders be coaxial; i.e.=, uniform spacing between them all around.
.
If the spac1ng is small compared
-
rect1on
effects
W1ll be negligible. From the equation above,
C:” Will
be in
centrmeters” (= e.s.u.). Dividing by
give m1cro-farads or by 9 X 1011 will give fârads.
(5) The current (i) due to the active material is the
whether the capac1ty 1s Cor C + Ca, and is equal to the rate of
ow (g/t) of quantity (g) of electricity. .Thus,
"
'
_
i = 9/f = OAV/f; = (C+ Co)AV/z2,
[
(17—3)
_
where .AV is the voltage change of the leaf system,— which is the
same in both cases since observations were made over the same
_
divisions in the eyepiece of the telescope'. It follows that the
capacity C of the leaf system can be computed from the equation.
Thus
.
,
__
'
"
'
C = Co —'-_
'
(17—4)
…
'
'
t2 — Î1
,
'
This will be in the same units as Co.
'
_
—
>-‘
.
_
,—
_
_
Iam'zaz‘ion Current.+F rom the voltage calibration curve, one
may determine the drop of potential AV corresponding to the
__
…
movement of the leaf over a denite number of divisions—. Substi—
;
‘
tation of17—4 in 17—3 gives '
'
_
_
Ï
—
;…
_
The same units are used"on—boths1desofdïeequatwn
' _
current z' divided by the chafgë (€)? oneach1onThus, ' . ']
Ÿ
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f
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amperesor 3X1®“368uThenthe°harge@fea°hwnbemg
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