452
PROBLEMS
.
3—1. What wave-length is to be associated with an electron of velocity
9 X 109 cm. per sec. to give its observed diffraction pattern? lnclude
the relativity correction for mass.
(0.077 Â)
3—2. Calculate the constant relating the wave-length of an electron
in angstroms with its accelerating potential in volts. Neglect the rela—
tivity correction.
3—3. What wave-length is to be associated with an electron acceler.ated by 50,000 volts to give its observed diffraction pattern? Neglect
the relativity correction.
(0.055 Â)
3—4. The wave—length associated with an electron is measured from
the space lattice of a nickel crystal and found to be 00566 angstrom.
The electrons were accelerated by 46,500 volts.
Compute Planck’s
constant, assuming the mass of the electrons to be 9.0 X 10_28 gram
ar‘1d neglecting the relativity correction.
_
-
length 0.389 A outside the metal, nickel. What is the change in wavelength upon entering the metal, if the surface energy is 16 volts? Find the
index of refraction of the metal for electrons of this wave—length.
3—6. Théposition of an electron is known to within 100 Â. What is
..
the uncertainty inthe determination of its velocity?
3—7. What wave-length is to be associated with a proton accelerated
by 50,000 volts? Neglect relativity correction.
,
4—1. How many ergs of work are needed to remove an electron from
the surface of sodium metal whose photo-electric long wave-length limit
is 6800 angstroms?
(Greater than 2.89 X ]0“12 erg = 1.82 volts)
4—2. What potential must be applied across two zinc plates when
one
of them is illuminated by light of wave-length 2536 angstroms in
order to repel the fastest electrons ejected? The work function of zinc'
j
13 3.89 volts.
(0.987 volt)
.
,
_.
'
4—3. ' If the work function of» tungsten is 4.52 volts, how many ergs of
,
WOrk are-needed‘to remove«an
electron from its surface?
'
.
_
,
_
Ÿ
are received ona surface 2 feet from the
source}
the candle power? What will be the illumination at
twiçç,çhcædiStarægeiï … ,
.
_.
.
]
,
—
.
What 13 the light ux «in lumens passing through an area of “1 sq.iri‘.
…
atad15tanœof 2ftfr0mthe
ProblemH?
,
fadïat10nlS of max1mumvmbilltÿ,convertthlS _
uxt°watts f1fthesourceïs 660 wattlampwhati31tseic1encyP
—
PROBLEMS
.
3—1. What wave-length is to be associated with an electron of velocity
9 X 109 cm. per sec. to give its observed diffraction pattern? lnclude
the relativity correction for mass.
(0.077 Â)
3—2. Calculate the constant relating the wave-length of an electron
in angstroms with its accelerating potential in volts. Neglect the rela—
tivity correction.
3—3. What wave-length is to be associated with an electron acceler.ated by 50,000 volts to give its observed diffraction pattern? Neglect
the relativity correction.
(0.055 Â)
3—4. The wave—length associated with an electron is measured from
the space lattice of a nickel crystal and found to be 00566 angstrom.
The electrons were accelerated by 46,500 volts.
Compute Planck’s
constant, assuming the mass of the electrons to be 9.0 X 10_28 gram
ar‘1d neglecting the relativity correction.
_
-
length 0.389 A outside the metal, nickel. What is the change in wavelength upon entering the metal, if the surface energy is 16 volts? Find the
index of refraction of the metal for electrons of this wave—length.
3—6. Théposition of an electron is known to within 100 Â. What is
..
the uncertainty inthe determination of its velocity?
3—7. What wave-length is to be associated with a proton accelerated
by 50,000 volts? Neglect relativity correction.
,
4—1. How many ergs of work are needed to remove an electron from
the surface of sodium metal whose photo-electric long wave-length limit
is 6800 angstroms?
(Greater than 2.89 X ]0“12 erg = 1.82 volts)
4—2. What potential must be applied across two zinc plates when
one
of them is illuminated by light of wave-length 2536 angstroms in
order to repel the fastest electrons ejected? The work function of zinc'
j
13 3.89 volts.
(0.987 volt)
.
,
_.
'
4—3. ' If the work function of» tungsten is 4.52 volts, how many ergs of
,
WOrk are-needed‘to remove«an
electron from its surface?
'
.
_
,
_
Ÿ
are received ona surface 2 feet from the
source}
the candle power? What will be the illumination at
twiçç,çhcædiStarægeiï … ,
.
_.
.
]
,
—
.
What 13 the light ux «in lumens passing through an area of “1 sq.iri‘.
…
atad15tanœof 2ftfr0mthe
ProblemH?
,
fadïat10nlS of max1mumvmbilltÿ,convertthlS _
uxt°watts f1fthesourceïs 660 wattlampwhati31tseic1encyP
—