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Part ll Test 4 Phys. 245. Name
tD#
Questions 16-19 are 10 points each. Show allwork.
16.)
A) How much work is required to accelerate a proton from rest up to a speed of O.997c?
What would be the momentum of this
proton?
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17.) When UV light of wavelength 250 nm falls on a metal surface, the maximum kinetic energy of the
emitted electrons is 1.50 eV. What is the work function of this metal? What is the stopping potential?
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18') What are the largest and smallest possible values for the angular momentum L of an electron
in the
n = 5 shell?
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19.) A cancer patient is undergoing radiation therapy in which protons with an energy of 1.2 MeV
(kinetic) are incident on a 0.25 kg tumor. A) lf the patient receives an effective
dose of 1.0 rem, what
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Physics 245 Test 4 Summer 2011 Professor Neil Goldman Version A
Name
ID#
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) An electron is accelerated through 100 kV. By what factor has its mass increased with respect to its
rest mass?
c)
1)
D) 8.00
1.s5
2)
A) due to the creation of chemical impurities.
B) the creation of new isotopes within the body.
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VD)
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3) Consider two spaceships, each traveling at 0.50c in a straight line. Ship A is moving directly away
from the Sun and ship B is approaching the Sun. The science officers on each ship measure the
velocity of light coming from the Sun. What do they measure for this velocity?
;\Ship A measures it as less than c, and ship B measures it as greater than c.
(9b" both ships it is measured to be exactly c.
C) On both ships it is measured to be less than c.
D) Ship B measures it as less than c, and ship A measures it as greater than c.
3)
4) The binding energy of the hydrogen atom in its ground state is -13.6 eV. \A/hat is the energy when
it is in the n = 5 state?
A)
B)
C)2.72eY
D) -0.544 eV
4)
,' L
il''e
h1/
)
ionizatron.
dr.te to
-2.72eY.
H
0.544eV
tr'
5) The energy bf an electron state has an uncertainty of about 0.500 eV. \z\rhat is the uncertainty in the
life-time of the level?
C) 8.28
0
IS
"
10-15 s
wffil
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D) 732 ' 10-11
I o''o t
activity now if the half-life
s)
s
is
6)
D) 3.3 pCi
7) According to the Bohr model of the atom, the angular momentum of an electron around the
7)
nucleus
A
multiple of h.
;j;".:";Hffi'ffi::"ililJuii"""""..szero
ffi*
(in MeV) is
8) A carbon-14 nucleus decays to a nitrogen-14 nucleus bybetadecay. Ho"/#iln
"nergy
released if carbon-14 has 9.atffiftt€03f 42y and nitrogen-14 has a mass of 1L0
A) 1.57 MeV
B) 0.157 MeV
C) 15.7 MeV
8)
9) \A/hat is the wavelength corresponding to the most intense light emitted by a giant star of surface
e)
B) 582 nm
/
bT z L?Wto*^K
a 2,1 po4 , I rfh
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C) 576 nm
f ro N;1
D)578 nm
10) Ig.aly{4ogen atom, an electron with n = 7 can exist in how many different quantum states?
10)
11) \Alhen a p+ particle is emitted from an unstable nucleus, the atomic number of the
11)
W= T{.dtt;J:l*r+"+;s+t xL J'1,
nucleus
A) does not
qQ-d".*gt"r bt 1J
changte.
C) increases by 1.
L2) A
D) none of the given answers
unit that measures the effective dose of radiation
A)
B)
curie.
i.j\$una4
gg
iq
th"
12)
D) RBE.
13)Inthegroundstate,thequantumnumbers(n,l,m|,m5)forhydrogenare,IeSPectivel_13)
A)
1,0,0,0.
B)1,,'1,,1,,+U2. C)1,'1.,1.",7.
W
X-ray technician takes an average of ten X-rays per day and receives 2.5 mrad per X-ray.
g t{e technician receives in 250 working days?
A) 6.25 rem
B) 7.75 rcm
D) 5.00 rem
14) An
lf Wy x,2f : f,,Afirn
15) \Mhat is the momentum in kg.m7s of a proton when
A) 1.2 ' 10-19 kg.m/s
C) 3.0 10-19 kg.m/s
'
f =hf
=
Cqr
=-l)
[email protected]
speed of 0.60c?
What
14)
15)
r
,6c z /,a r [ 6PF/n -?t
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