Physics 228  Exam 2
8 April 2010
Profs. Rabe and Coleman
=
⇒
Your
name
sticker
with
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Turn off and put away cell phones now!
1.
The exam will last from 9:40pm to 11:00pm.
2.
Use a #2 pencil to make entries on the answer sheet. Enter the
following ID information now, before the exam starts.
3.
In the section labelled NAME (Last, First, M.I.) enter your last
name, then fill in the empty circle for a blank, then enter your
first name, another blank, and finally your middle initial.
4.
Under STUDENT # enter your 9digit student ID.
5.
Enter 228 under COURSE, and your section number (see label
above) under SEC.
6.
Under CODE enter the exam code given above.
7.
During the exam, you may use pencils, a calculator, and one
handwritten
8.5 x 11 inch sheet with formulas and notes, with
out attachments.
8.
There are 16 multiplechoice questions on the exam.
For each
question, mark only one answer on the answer sheet. There is no
deduction of points for an incorrect answer, so even if you cannot
work out the answer to a question, you should make an educated
guess. At the ened of the exam,
hand in the answer sheet and
the cover page.
Retain this question paper for future reference
and study.
9.
When you are asked to open the exam, make sure that your copy
contains all 16 questions. Raise your hand if this is not the case,
and a proctor will help you. Also raise your hand during the exam
if you have a question.
10.
Please SIGN the cover sheet under your name sticker and have
your student ID ready to show to the proctor during the exam.
Useful information
c
= speed of light = 3
.
00
×
10
8
m/s
q
e
=

e
= charge on an electron =

1
.
602
×
10
−
19
Coulombs
q
p
= +
e
= charge on a proton = +1
.
602
×
10
−
19
Coulombs
m
e
= electron mass = 9
.
11
×
10
−
31
kg
m
e
c
2
= electron rest energy = 0
.
511 MeV
m
p
= proton mass = 1
.
67
×
10
−
27
kg
m
p
c
2
= proton rest energy = 938
.
27
MeV
m
n
c
2
= neutron rest energy = 939
.
57
MeV
k
B
= Boltzmann’s constant = 1
.
38
×
10
−
23
J/K
Wien’s Constant = 2
.
898
×
10
−
3
m
·
K
σ
= Stefan’s Constant = 5
.
670
×
10
−
8
W/
(
m
2
K
4
)
¯
h
=
h
2
π
h
= 6
.
626
×
10
−
34
Js
h
= 4
.
136
×
10
−
15
eVs (in units of electron voltssecond)
hc
= 1240 eV
·
nm = 1240 MeV
·
fm
1 nm = 10
−
9
m
1
˚
A = 10
−
10
m = 0.1 nm
1
μ
m = 10
−
6
m
1 mHz = 10
−
3
Hz
1 kHz = 10
+3
Hz
1 MHz = 10
+6
Hz
1 GHz = 10
+9
Hz
1
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1.
A photon, an electron, and a baseball have the same momentum.
Which has the largest de Broglie wavelength?
a)
photon
b)
all have the same wavelength
c)
electron
d)
baseball and electron
e)
baseball
2.
A particle is confined inside a cube of side length
L
, with one
corner at the origin. The potential height of the walls of the cube
is infinite. The normalized wave function of the particle, which is
in the ground state, is
ψ
(
x,y,z
) =
parenleftbigg
2
L
parenrightbigg
3
/
2
sin
πx
sin
πy
sin
πz,
0
<x, y, z<L
What is the maximum value of the probability distribution func
tion for an electron in this state?
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 Spring '08
 Staff
 Physics, Electron, 10−19 Coulombs, υE

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