Computational Methods: for Scientists and
Engineers 3rd Edition by Morrison Chapters 1- 15
,Table of contents FGH FGH
1. The Wave-Particle Duality
FGH FGH FGH
2. The Schrödinger Wave Equation
FGH FGH FGH FGH
3. Operators and Waves
FGH FGH FGH
4. The Hydrogen Atom
FGH FGH FGH
5. Many-Electron Atoms
FGH FGH
6. The Emergence of Masers and Lasers
FGH FGH FGH FGH FGH FGH
7. Diatomic Molecules
FGH FGH
8. Statistical Physics
FGH FGH
9. Electronic Structure of Solids
FGH FGH FGH FGH
10. Charge Carriers in Semiconductors
FGH FGH FGH FGH
11. Semiconductor Lasers
FGH FGH
12. The Special Theory of Relativity
FGH FGH FGH FGH FGH
13. The Relativistic Wave Equations and General Relativity
FGH FGH FGH FGH FGH FGH FGH
14. Particle Physics
FGH FGH
15. Nuclear Physics
FGH FGH
,1
The Wave-Particle Duality - Solutions
F G H F G H F G H F G H
1. The energy of photons in terms of the wavelength of light is g
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
iven by Eq. (1.5). Following Example 1.1 and substituting λ =
FGH FGH FGH FGH FGH F G H FGH FGH FGH FGH F
200 eV gives:
GH FGH FGH
hc 1240 eV · nm
= = 6.2 eV
FG H F G H FGH
Ephoton = λ
FGH FGH
200 nm FGH FGH
2. The energy of the beam each second is:
F G H F G H F G H F G H F G H F G H F G H
power 100 W
= = 100 J
FGH
Etotal = time
FGH FGH
1s FGH FGH
The number of photons comes from the total energy divided by
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
the energy of each photon (see Problem 1). The photon’s energy
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
must be converted to Joules using the constant 1.602 × 10−19 J/
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
eV , see Example 1.5. The result is:
FGH FGH FGH FGH FGH FGH FGH
N =Etotal = 100 J = 1.01 × 1020 FGH F G H FGH
photons E
FGH FGH FGH
pho
ton 9.93 × 10−19 FGH FGH
for the number of photons striking the surface each second.
F G H F G H F G H F G H F G H F G H F G H F G H F G H
3.We are given the power of the laser in milliwatts, where 1 mW =
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
10−3 W . The power may be expressed as: 1 W = 1 J/s. Followin
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
g Example 1.1, the energy of a single photon is:
FGH FGH FGH FGH FGH FGH FGH FGH FGH
1240 eV · nm
hc = 1.960 eV
FG H F G H FGH
Ephoton = 632.8 nm
FGH FGH FGH
F G H FGH
=
λ
F G H
F G H
We now convert to SI units (see Example 1.5):
FGH FGH FGH FGH FGH FGH FGH F G H
1.960 eV × 1.602 × 10−19 J/eV = 3.14 × 10−19 J
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
Following the same procedure as Problem 2: FGH FGH FGH FGH FGH FGH
1 × 10−3 J/s 15 photons FGH FGH FGH
F G H
Rate of emission = = 3.19 × 10
3.14 × 10−19 J/photon s
FGH F G H FGH F G H FGH FGH FGH
F G H
FGH FGH F G H
, 2
4. The maximum kinetic energy of photoelectrons is found usi
FGH FGH FGH FGH FGH FGH FGH FGH
ng Eq. (1.6) and the work functions, W, of the metals are given
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
in Table 1.1. Following Problem 1, Ephoton = hc/λ = 6.20 eV .
FGH FGH FGH FGH F G H F G H FGH FGH FGH FGH F G H FGH F G H
For part (a), Na has W = 2.28 eV :
F G H F G H F G H F G H F G H F G H FGH F G H FGH
(KE)max = 6.20 eV − 2.28 eV = 3.92 eV FGH FGH FGH F GH FGH FGH F GH FGH FGH
Similarly, for Al metal in part (b), W = 4.08 eV giving (KE)max = 2.12 e FGH FGH FGH FGH FGH FGH FGH F G H FGH FGH F G H FGH FGH FGH FGH
V
and for Ag metal in part (c), W = 4.73 eV , giving (KE)max = 1.47 eV .
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
5.This problem again concerns the photoelectric effect. As in Pro
FGH FGH FGH FGH FGH FGH FGH FGH FGH
blem 4, we use Eq. (1.6): FGH FGH FGH FGH FGH
hc − FGH
(KE)max = FGH
Wλ
FGH
FGH
where W is the work function of the material and the term
F G H F G H F G H F G H F G H F G H F G H F G H F G H F G H F G H F G
Hhc/λ describes the energy of the incoming photons. Solving for the
F G H FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
latter:
hc
= (KE)max + W = 2.3 eV + 0.9 eV = 3.2 eV
λ
FGH FGH FGH F G H FGH FGH F G H FGH F GH F G H FGH FGH
F G H
Solving Eq. (1.5) for the wavelength: FGH F GH FGH FGH FGH
1240 eV · nm
λ=
FG H F G H FGH
= 387.5 nm FGH
3.2 e
FGH FGH
F G H
V
6. A potential energy of 0.72 eV is needed to stop the flow of electron
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
s. Hence, (KE)max of the photoelectrons can be no more than 0.72 eV
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
. Solving Eq. (1.6) for the work function:
FGH FGH FGH FGH FGH FGH FGH
hc 1240 eV · — 0.72 eV = 1.98 eV
W= —
FG H F G H FGH
λ nm
FGH FG H F G H FGH FGH
FGH F G H
(KE)max F
= G H
460 nm FGH
7. Reversing the procedure from Problem 6, we start with Eq. (1.6): FGH FGH FGH FG H FGH FGH FGH F G H FGH FGH
hc
− W 1240 eV · — 1.98 eV = 3.19 eV
F G H
(KE)max =
FG H F G H FGH
FGH F G H
nm
FGH FGH FG H F G H FGH FGH
=
λ
240 nm FGH
Hence, a stopping potential of 3.19 eV prohibits the electrons fro
FGH FGH FGH FGH FGH FGH FGH FGH FGH FGH
m reaching the anode.
FGH FGH FGH
8. Just at threshold, the kinetic energy of the electron
F G H F G H F G H F G H F G H F G H F G H F G H F
G H is zero. Setting (KE)max = 0 in Eq. (1.6),
F G H F G H FGH FGH FGH F G H F G H F G H
hc
W= = 1240 eV · = 3.44 eV FG H F G H FGH
λ0
FGH
nm
FGH FGH
360 nm FGH