PROBLEMS .
'
453
4—7. If the source of problem
4—4 is used to illùminate a photo-cell of
1 sq. cm. area
and sen31t1v1ty of 40 microamps per lumen at a distance of
1 ft., what IS the output of the cell … amperes?
What is
the maximum frequency of x—rays from an X-ray tube
hav1ng an applied potential difference of 100,000 volts?
_.5—1. What Will be the root—mean-square value of the uctuating current in the inductance—capacitance circuit in the plate circuit, as in the
shot effect,
if the
effective resistance of the coil is 5 ohms, the capacity
1s 600 m1cro-m1crofarads and the plate current is 5 milliamperes?
'
(0.364 microampere)
5—2. If the work function of platinum is 6.27 volts, how many ergs of
work are needed to remove an electron from its surface?
'
,
5—3. Compute the constant in Richardson’s .equation (5—3) if the
_
emission from each 'square centimeter of a tungsten lament at 2000°
absolute is 4.2 milliamperes. The work function
of tungsten is 4.52 volts.
5—4. What is the total current in amperes per sq. cm. from a tungsten
lament at a temperature of 2000° K, where the eld intensity is 2000
_
volts per cm.
For 11 of Richardson’s equation use 60.2 amps._ per cm.2 f
per degree.2
‘
6—1. Compute the constant in the Child-Langmuir equation when the
space-charge-limited current is 5.627 milliamperes and the plate potential
is 180 volts.
_
.
6—2. A change of 10 volts in the plate_potèntial of a three-electrode
_
tube causes a change of 0.833 milliampere
in its plate current. Com,
pute the plate resistance of the tube.
_
(12,000
6—3. The mutual conductance of a
675 micro—
-
mhos and the plate resistance is 12,000 ohms._
,
_
constant?
‘
'
'
‘
'
'
6—4. How many volts
tube
_
whose amplication
ohms
_
…
needed ee change
-
Ï‘! '
6—5. Find the
“‘ focallengthOfamagnetlceld0fBOoerStedsngak
_
angle of 5° With the€l€Ctmnbeam)Whentheele€tron8haveeen
‘
—‘
Ê6—6. Find thefocallengthofadoubl‘îgaulelensWheœth‘îr""°hus°f
«'
'
453
4—7. If the source of problem
4—4 is used to illùminate a photo-cell of
1 sq. cm. area
and sen31t1v1ty of 40 microamps per lumen at a distance of
1 ft., what IS the output of the cell … amperes?
What is
the maximum frequency of x—rays from an X-ray tube
hav1ng an applied potential difference of 100,000 volts?
_.5—1. What Will be the root—mean-square value of the uctuating current in the inductance—capacitance circuit in the plate circuit, as in the
shot effect,
if the
effective resistance of the coil is 5 ohms, the capacity
1s 600 m1cro-m1crofarads and the plate current is 5 milliamperes?
'
(0.364 microampere)
5—2. If the work function of platinum is 6.27 volts, how many ergs of
work are needed to remove an electron from its surface?
'
,
5—3. Compute the constant in Richardson’s .equation (5—3) if the
_
emission from each 'square centimeter of a tungsten lament at 2000°
absolute is 4.2 milliamperes. The work function
of tungsten is 4.52 volts.
5—4. What is the total current in amperes per sq. cm. from a tungsten
lament at a temperature of 2000° K, where the eld intensity is 2000
_
volts per cm.
For 11 of Richardson’s equation use 60.2 amps._ per cm.2 f
per degree.2
‘
6—1. Compute the constant in the Child-Langmuir equation when the
space-charge-limited current is 5.627 milliamperes and the plate potential
is 180 volts.
_
.
6—2. A change of 10 volts in the plate_potèntial of a three-electrode
_
tube causes a change of 0.833 milliampere
in its plate current. Com,
pute the plate resistance of the tube.
_
(12,000
6—3. The mutual conductance of a
675 micro—
-
mhos and the plate resistance is 12,000 ohms._
,
_
constant?
‘
'
'
‘
'
'
6—4. How many volts
tube
_
whose amplication
ohms
_
…
needed ee change
-
Ï‘! '
6—5. Find the
“‘ focallengthOfamagnetlceld0fBOoerStedsngak
_
angle of 5° With the€l€Ctmnbeam)Whentheele€tron8haveeen
‘
—‘
Ê6—6. Find thefocallengthofadoubl‘îgaulelensWheœth‘îr""°hus°f
«'