102
5.
THERMIONIC EMISSION
the tube in parallel With each other. C is the capacity of the
condenser in farads, L is the inductance of the coil in henries and
the average
of the squared voltages across C. The latter is
deduced from the gain of the amplier and the reading of the meter
M.
The reading of the plate milliammeter, is amperes, carries
the subscript & to denote an important condition in the experi—
.
mental procedure, namely, that the voltage of the battery B shall
_
_be Suiciently high (several hundred volts) that all electrons
emitted by the lament shall be drawn over to the plate; no
“
space
-
charge” is left in the vacuum.
-
Hull and Williams4 measured the charge 6, using equation 5—1.*
They found the value
'
e =‘ 1.586 X 10“19 coulombs
or
'
=
4.758 X 10*10 e.s.u.
which is within a fraction of one per
cent of the accepted value for
the charge of the electron.
The voltage developed across the
would have been equal to zero if the electricity had been '
emitted by the lament in a steady stream and would have been
1.4 times as large as that which was observed had each of the
charges leaving the lament been twice that of an electron. These
extremes of voltage are well beyond the experimental errors. In
the light of this work and -the e/m experiments, we see that elec—
irons are emitted by a hot lament in a vacuum.
'A noise 5 Will be heard in a loud speaker used in place of the
meter M of gure 5—3, due to the shoteffect. If a space charge
exists between the lament
plate, due to too low a Voltage at
.
,
B, as isusual in ampliers, the JÏZ_0Î noise is lessened. In addition
sh0t effect, there are a number of other causes for amplier
_
"noises, It is
course, that the disturbances due to poor
,
.connections, batteries, resistors, etc., have been.
'
Among these additional. noises may be mentioned the errat1c
changes in plate current5resulting“ from the evap0ration of::iè
'
material itself,
the ic/ear ecz‘, and from
'
In this W0Ïk, they developed the screen grid tube which has become
Ï ' '
;in order» .to,
rad1°
t *ff?‘lë91©8“à
“ofj‘th“e L‘O- cire—uit ‘Was in the broadcast
-'
£, range
1400 meœr,s
was used.
v.-
5.
THERMIONIC EMISSION
the tube in parallel With each other. C is the capacity of the
condenser in farads, L is the inductance of the coil in henries and
the average
of the squared voltages across C. The latter is
deduced from the gain of the amplier and the reading of the meter
M.
The reading of the plate milliammeter, is amperes, carries
the subscript & to denote an important condition in the experi—
.
mental procedure, namely, that the voltage of the battery B shall
_
_be Suiciently high (several hundred volts) that all electrons
emitted by the lament shall be drawn over to the plate; no
“
space
-
charge” is left in the vacuum.
-
Hull and Williams4 measured the charge 6, using equation 5—1.*
They found the value
'
e =‘ 1.586 X 10“19 coulombs
or
'
=
4.758 X 10*10 e.s.u.
which is within a fraction of one per
cent of the accepted value for
the charge of the electron.
The voltage developed across the
would have been equal to zero if the electricity had been '
emitted by the lament in a steady stream and would have been
1.4 times as large as that which was observed had each of the
charges leaving the lament been twice that of an electron. These
extremes of voltage are well beyond the experimental errors. In
the light of this work and -the e/m experiments, we see that elec—
irons are emitted by a hot lament in a vacuum.
'A noise 5 Will be heard in a loud speaker used in place of the
meter M of gure 5—3, due to the shoteffect. If a space charge
exists between the lament
plate, due to too low a Voltage at
.
,
B, as isusual in ampliers, the JÏZ_0Î noise is lessened. In addition
sh0t effect, there are a number of other causes for amplier
_
"noises, It is
course, that the disturbances due to poor
,
.connections, batteries, resistors, etc., have been.
'
Among these additional. noises may be mentioned the errat1c
changes in plate current5resulting“ from the evap0ration of::iè
'
material itself,
the ic/ear ecz‘, and from
'
In this W0Ïk, they developed the screen grid tube which has become
Ï ' '
;in order» .to,
rad1°
t *ff?‘lë91©8“à
“ofj‘th“e L‘O- cire—uit ‘Was in the broadcast
-'
£, range
1400 meœr,s
was used.
v.-