Computational Methods: for Scientists and
Engineers 3rd Edition by Morrison Chapters 1- 15
,Table of contents
T T
1.TTheTWave-ParticleTDuality
2.TTheTSchrödingerTWaveTEquation
3.TOperatorsTandTWaves
4.TTheTHydrogenTAtom
5.TMany-ElectronTAtoms
6.TTheTEmergenceTofTMasersTandTLasers
7.TDiatomicTMolecules
8.TStatisticalTPhysics
9.TElectronicTStructureTofTSolids
10.TChargeTCarriersTinTSemiconductors
11.TSemiconductorTLasers
12.TTheTSpecialTTheoryTofTRelativity
13.TTheTRelativisticTWaveTEquationsTandTGeneralTRelativity
14.TParticleTPhysics
15.TNuclearTPhysics
,1
TheT Wave-ParticleT DualityT -T Solutions
1. TheTenergyTofTphotonsTinTtermsTofTtheTwavelengthTofTlightTisTg
ivenTbyTEq.T(1.5).TFollowingTExampleT 1.1TandTsubstitutingTλT=T
200TeVTgives:
hc 1240T eVT ·Tnm
= =T6.2TeV
EphotonT= λ 200Tnm
2. TheT energyT ofT theT beamT eachT secondT is:
power 100T W
= =T100TJ
EtotalT= time 1T s
TheTnumberTofTphotonsTcomesTfromTtheTtotalTenergyTdividedTbyT
theTenergyTofTeachTphotonT(seeTProblemT1).TTheTphoton’sTenergyT
mustTbeTconvertedTtoTJoulesTusingTtheTconstantT1.602T×T10−19TJ/
eVT,TseeTExampleT1.5.TTheTresultTis:
N =TEtotalT = 100TJ =T1.01T×T1020
photons E
pho
ton 9.93T×T10−19
forT theT numberT ofT photonsT strikingT theT surfaceT eachT second.
3.WeTareTgivenTtheTpowerTofTtheTlaserTinTmilliwatts,TwhereT1TmWT
=T10−3TWT.TTheTpowerTmayTbeTexpressedTas:T1TWT=T1TJ/s.TFollow
ingTExampleT1.1,TtheTenergyTofTaTsingleTphotonTis:
1240T eVT ·Tnm
hcT =T1.960TeV
EphotonT =T 632.8T nm
=
λT
WeT nowT convertT toT SITunitsT (seeT ExampleT 1.5):
1.960TeVT×T1.602T×T10−19TJ/eVT =T3.14T×T10−19TJ
FollowingT theT sameT procedureT asTProblemT 2:
1T×T10−3TJ/s 15T photons
RateTofT emissionT=T = T3.19T×T10
3.14T×T10−19T J/photonT s
, 2
4.TheTmaximumTkineticTenergyTofTphotoelectronsTisTfoundTusin
gTEq.T(1.6)TandTtheTworkTfunctions,TW,TofTtheTmetalsTareTgivenTin
TTableT1.1.TFollowing TProblemT 1,T EphotonT=Thc/λT=T6.20T eV T.T ForT p
artT (a),T NaT hasT WT =T2.28T eVT:
(KE)maxT=T6.20TeVT−T2.28TeVT =T3.92TeV
Similarly,TforTAlTmetalTinTpartT(b),TWT =T4.08TeVT givingT(KE)maxT=T2.12TeV
andTforTAgTmetalTinTpartT(c),TWT=T4.73TeVT,TgivingT(KE)maxT=T1.47TeVT.
5.ThisTproblemTagainTconcernsTtheTphotoelectricTeffect.TAsTinTProb
lemT4,TweTuseTEq.T(1.6):
hcT−T
(KE)maxT =
WTλ
whereT WT isT theT workT functionT ofT theT materialT andT theT termT hc/λT de
scribesTtheTenergyTofTtheTincomingTphotons.TSolvingTforTtheTlatter:
hc
=T(KE)maxT+TWT =T2.3TeVT +T0.9T eVT =T3.2T eV
λT
SolvingTEq.T(1.5)TforTtheTwavelength:
1240T eVT ·Tnm
λT= =T387.5Tnm
3.2T e
V
6. ATpotentialTenergyTofT0.72TeVTisTneededTtoTstopTtheTflowTofTelectrons.
THence,T(KE)max TofTtheTphotoelectronsTcanTbeTnoTmoreTthanT0.72TeV
.TSolvingTEq.T(1.6)TforTtheTworkTfunction:
hc 1240T eVT ·Tn —T0.72T eVT =T1.98T eV
W T =T —
λ m
(KE)maxT
=
460Tnm
7. ReversingT theT procedureT fromT ProblemT 6,T weT startT withT Eq.T (1.6):
hcT 1240T eVT ·Tn
(KE)maxT = −TWT —T1.98T eVT =T3.19T eV
= m
λ
240Tnm
Hence,TaTstoppingTpotentialTofT3.19TeVTprohibitsTtheTelectronsTfromT
reachingTtheTanode.
8. JustT atT threshold,T theT kineticT energyT ofT theT electronT isT zer
o.T SettingT(KE)maxT=T0T inT Eq.T (1.6),
hc
WT= = 1240T eVT ·Tn =T3.44T eV
λ0 m
360Tnm
9. ATfrequencyTofT1200TTHzTisTequalTtoT1200T×T1012THz.TUsingTEq.T(1.10),