—
EXPERIMENT ,4:—1
_
-
91
diameter, to permit the light from the lamp to reach the cell, and
_
are so spaced that direct external rays of light cannot enter the
'
"
cell, as indicated by the dotted lines._ Even when dead ”black, the
diaphragms scatter a small amouhtof light into the cell.
The lamp should be supplied from' a Constant voltage source;
'
i.e., V
,
in the gure is to be kept constant. "The photoelectric
'
currents can be measured with an ordinary wall galvanome”terï
provided with a shunt. A protective resistance of 5000 ohms,
more, is placed in series with the cell circuit.
‘
'
Premutz'om.—(l) The distance from the lamp to the cell should.
never be less‘than 30 or 40 centimeters.
(2) The voltage applied
to a gas lled Cell should never exceed 80 or 90 volts.
:
term
‘Ÿ galvanometer deection,” as used
below,
difference between the-observed deections with
_
lamp on_ and ofî. For the _brighter lights, this correction for
.
Scattered light is ,negligible,but for Weak illumination of the cell it
"
may amount to fty per
Cent.
as follows: (1) With a 40
=
Watt lamp “at a Xed distance of 70 centimeters from a gas lled cell, '
vary'th'e‘voltage
from 0 to 80 volts and record galvanometer .
-
deections. Ten points will suice. Repeat with a vacuum cell
ad*plm bôth'”cürve”sôn the same graph; - galvahometer deections
_
vertically
horizontally. (2) With a constant pote—
f
t1alof 70 volts(E)on
cell, vary the distance d— from30
t0300œnt1metersrecordmggalvanometerdeeetwns TenP°mts
Wlsuîœ Thethreedwphmgmsm _hæd tobereadiusæd
SquarwfthedmtanœdPiotgalvanometerdeectwn3V€fücaY
example(l)hghtmœnsüyefalampPeratedatvarwusvdtages
hght(3)theeffect0fvarwusreecœrsa°k@f0ramndthelamp—
and(4)measurementoftheabsorptwnfsm®kertransluœnt
EXPERIMENT ,4:—1
_
-
91
diameter, to permit the light from the lamp to reach the cell, and
_
are so spaced that direct external rays of light cannot enter the
'
"
cell, as indicated by the dotted lines._ Even when dead ”black, the
diaphragms scatter a small amouhtof light into the cell.
The lamp should be supplied from' a Constant voltage source;
'
i.e., V
,
in the gure is to be kept constant. "The photoelectric
'
currents can be measured with an ordinary wall galvanome”terï
provided with a shunt. A protective resistance of 5000 ohms,
more, is placed in series with the cell circuit.
‘
'
Premutz'om.—(l) The distance from the lamp to the cell should.
never be less‘than 30 or 40 centimeters.
(2) The voltage applied
to a gas lled Cell should never exceed 80 or 90 volts.
:
term
‘Ÿ galvanometer deection,” as used
below,
difference between the-observed deections with
_
lamp on_ and ofî. For the _brighter lights, this correction for
.
Scattered light is ,negligible,but for Weak illumination of the cell it
"
may amount to fty per
Cent.
as follows: (1) With a 40
=
Watt lamp “at a Xed distance of 70 centimeters from a gas lled cell, '
vary'th'e‘voltage
from 0 to 80 volts and record galvanometer .
-
deections. Ten points will suice. Repeat with a vacuum cell
ad*plm bôth'”cürve”sôn the same graph; - galvahometer deections
_
vertically
horizontally. (2) With a constant pote—
f
t1alof 70 volts(E)on
cell, vary the distance d— from30
t0300œnt1metersrecordmggalvanometerdeeetwns TenP°mts
Wlsuîœ Thethreedwphmgmsm _hæd tobereadiusæd
SquarwfthedmtanœdPiotgalvanometerdeectwn3V€fücaY
example(l)hghtmœnsüyefalampPeratedatvarwusvdtages
hght(3)theeffect0fvarwusreecœrsa°k@f0ramndthelamp—
and(4)measurementoftheabsorptwnfsm®kertransluœnt