.
l
l
ll
1—5.
THE THERMIQNIC METHOD
_
7
1—5.
The Thermionic Method.—.-A hot lani‘ent, sealed in a
highly evacuated tube, emits negative electricity in amounts which «
vary slightly around an average value from one moment to the
’
next.
The nature of the irregularities in this varying current of
electricity Will be different if the emission consists of large numbers
of discrete charges than if it consists of a continuous ow of electricity. The examination of these irregularities will be discussed
in Chapter 5 under the title of “The Shot Effect.” The result of
a series of careful experiments shows that the electricity is emitted
as discrete charges of amount
€ = 4.76 X 10"10 e.s.u.
_
which is in reasonable agreement with the value obtained for the
charge of the electron by the oil—drop method, although the
'
accuracy is not so great.
—
'
Ï
'
1—6.
The Charge of the Alpha Particle.—Cçrtain radioactive
substances, radium, for example, Spontaneously throw out posi—
tively charged bodies called alpha particles. In order to measure
_
the charge on each alpha particle, a determination- is made of the
total amount of electricity carried by a known number of particles,
as described_in Chapter 12. The resultis
_
=
-
.
’
Ze = 2 >< (4.769:1: .oo4) >< 10—lO e.s.u.,
-
_
_
j
.
which is twice the
the electron as measured by the oil-‘
drop method. .;HoweVer, this Charge is
not negative.
.
”
1Ï—7.Ï
Fafaday.—The rst experimental evidence-for the
3
_… atomiciW Of electriCity appears in
which Faraday made
early1n the ninetçenth, century, f0f the passage
of electricity
throughsoluüonsHestatedasone 9‘f,
the laws ,9f,
«
: »»
-
thatthemassofthesubStanœhberatedatanelectr0delsdlrectly
“
proportwnalœthequantltY°felectrlüty S€ntthrou€hthe 80111 ' _
monFrexampleSincetheïnternatlonalElem0magnetmUmt
ofelectrlüty(tencoubmbs)ISenedasthat@uantltYWhmhm—
PassmgthroughastandafdsllVf80htlon W1Hd€POS“ 001118
gramsFrommanY$lmarcasesFaradaYwasabletoasseftthat
l
l
ll
1—5.
THE THERMIQNIC METHOD
_
7
1—5.
The Thermionic Method.—.-A hot lani‘ent, sealed in a
highly evacuated tube, emits negative electricity in amounts which «
vary slightly around an average value from one moment to the
’
next.
The nature of the irregularities in this varying current of
electricity Will be different if the emission consists of large numbers
of discrete charges than if it consists of a continuous ow of electricity. The examination of these irregularities will be discussed
in Chapter 5 under the title of “The Shot Effect.” The result of
a series of careful experiments shows that the electricity is emitted
as discrete charges of amount
€ = 4.76 X 10"10 e.s.u.
_
which is in reasonable agreement with the value obtained for the
charge of the electron by the oil—drop method, although the
'
accuracy is not so great.
—
'
Ï
'
1—6.
The Charge of the Alpha Particle.—Cçrtain radioactive
substances, radium, for example, Spontaneously throw out posi—
tively charged bodies called alpha particles. In order to measure
_
the charge on each alpha particle, a determination- is made of the
total amount of electricity carried by a known number of particles,
as described_in Chapter 12. The resultis
_
=
-
.
’
Ze = 2 >< (4.769:1: .oo4) >< 10—lO e.s.u.,
-
_
_
j
.
which is twice the
the electron as measured by the oil-‘
drop method. .;HoweVer, this Charge is
not negative.
.
”
1Ï—7.Ï
Fafaday.—The rst experimental evidence-for the
3
_… atomiciW Of electriCity appears in
which Faraday made
early1n the ninetçenth, century, f0f the passage
of electricity
throughsoluüonsHestatedasone 9‘f,
the laws ,9f,
«
: »»
-
thatthemassofthesubStanœhberatedatanelectr0delsdlrectly
“
proportwnalœthequantltY°felectrlüty S€ntthrou€hthe 80111 ' _
monFrexampleSincetheïnternatlonalElem0magnetmUmt
ofelectrlüty(tencoubmbs)ISenedasthat@uantltYWhmhm—
PassmgthroughastandafdsllVf80htlon W1Hd€POS“ 001118
gramsFrommanY$lmarcasesFaradaYwasabletoasseftthat