Download Period 1 - ND

PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS
For each of the following questions complete communication must be shown. Communication consists of an introduction to
the physics of the situation, diagrams, word explanations and calculations in a well laid out formula, substitution, and answer
format.
1. Answer the following questions concerning historical models of the atom. (10.00 marks)
a) Describe one contribution to our understanding of atomic structure that resulted from charge-to-mass ratio
measurements of atomic and subatomic particles.
b) Electrons, each with an initial kinetic energy close to 5·60 x 10-19 J, are fired through a gas. The graph below shows how
the number of electrons emerging from the gas varies as a function of their kinetic energies.
i) Assuming that the gas atoms were initially in their ground state (with energy E1 ) explain:
1. the reason for the peak at 5·60 x10 -19 J;
2. the cause of the other two peaks.
ii) Sketch a suitable energy-level diagram for the gas.
iii) Calculate three energies of photons emitted by the gas.
2. A polonium nucleus of atomic number 84 and mass number 210 decays to a nucleus of lead by the emission of an
alpha particle of mass 4.0026 atomic mass units and kinetic energy 5.5 MeV.
(1 atomic mass unit = 931.5 MeV/c2 = 1.66 x 10-27kg.) (10.00 marks)
a) Determine each of the following.
i. The atomic number of the lead nucleus
ii. The mass number of the lead nucleus
b) Determine the mass difference between the polonium nucleus and the lead nucleus, taking into account the kinetic
energy of the alpha particle but ignoring the recoil energy of the lead nucleus.
c) Determine the speed of the alpha particle.
d) Determine the De Broglie wavelength of the alpha particle.
The alpha particle is scattered from a gold nucleus (atomic number 79) in a "head-on" collision.
e) Write an equation that could be used to determine the distance of closest approach of the alpha particle to the gold
nucleus. It is not necessary to actually solve this equation.
3. While studying a radioactive phosphorus, 31 45P , it was discovered that a 128 g sample had decayed to 4.48 g after 60 s.
The following table provides data corresponding to the decay. (10.00 marks)
mass ( g )
time ( s )
128.0
73.0
41.9
23.9
13.7
7.80
4.48
0
10
20
30
40
50
60
a) Graph the data with the manipulated variable on the horizontal axis. Provide a suitable title for your graph.
b) Using your graph, or some other appropriate method, determine the half-life of this substance. Indicate how you
determined your answer.
c) Write the decay equation for the decay of 34-phosphorous, identifying the product isotope.
1
PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS

Choose the best response and place your answers, using HB pencil, on the Scantron sheet provided. 

1. Rutherford's scattering experiment disproved which atomic model?
a.
c.
Thomson's
Millikan's
b.
d.
Bohr's
quantum mechanical model
2.
A small particle moves horizontally at 3.0 x 106 m/s and enters a downward electric field produced by two horizontal
plates, 2.0 mm apart, connected to a 40 V battery. If the charge-to-mass ratio of the particle is
1.0 x 108 C/kg, the instantaneous acceleration is a.b x 10cd m/s2.
The values of a, b, c, and d are ______, ______, ______, and ______.
(Record all four digits of your answer on the answer sheet.)
3. Bohr explained the phenomenon of the hydrogen spectrum by hypothesizing that
a.
b.
c.
d.
electrons have angular momenta corresponding to the energies of light observed in the spectrum
discrete frequencies of light are emitted when a transition between two allowable energy states of the atom takes
place
the wavelengths of light observed in the spectrum correspond to the radii of the allowable orbitals of the atom
the electric influence of the electrons interacting with the magnetic influence of the nucleus produces
electromagnetic waves corresponding to the frequencies of the observed spectrum
4. Excited hydrogen atoms are all in the n = 3 state. How many different photon energies could possibly be emitted
as these atoms return to the ground state?
a.
1
b.
2
c.
3
d.
4
5. Which transition is associated with the largest change in energy in the hydrogen atom?
a.
n = 5 to n = 3
b.
n = 2 to n = 1
c.
n = 3 to n = 2
d.
n = 4 to n = 2
6. Complete the following statement: For the ground state of the hydrogen atom, the Bohr model correctly predicts
a.
c.
e.
only the energy.
only the angular momentum and the spin.
the energy, the angular momentum, and the spin.
b.
d.
only the angular momentum.
the angular momentum and the energy.
7.
In a scattering experiment, alpha particles with a kinetic energy of 1.5 x 10-12 J are fired at a thin metal foil. The speed
of the alpha particles is a.bc x 10d m/s.
The values of a, b, c, and d are ______, ______, ______, and ______.
(Record all four digits of your answer on the answer sheet.)
2
PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS
8. Which of the following is not a measurement unit for measuring the harmful effects of radiation.
a.
c.
Gray (Gy)
Sievert (Sv)
b.
d.
Relative biological effectiveness (RBE)
Becquerel (Bq)
9. Which of the following statements provides a reason for the use of nuclear fusion rather than nuclear fission as a
source of energy?
a.
b.
c.
d.
Fusion reactions can be produced in magnetic-field containment devices, whereas fission reactions require
nuclear reactors.
Fusion energy is in the form of heat, whereas fission energy is in the form of gamma radiation.
Fusion products are relatively harmless, whereas fission products are extremely hazardous.
Fusion reactions are economically feasible, whereas fission reactions are not.
10.
According to the graph, the time required for 80.0 g of arsenic-79 to decay to 10.0 g is ___ min.
(Record your two-digit answer on the answer sheet.)
Use the following information to answer the next ten questions.
A scanning electron microscope (SEM) is a microscope that uses a beam of electrons rather than visible light to produce
images of specimens.
Description of the Operation of an SEM
Electrons are accelerated from the electron gun to the anode. The electric potential difference between the electron gun and the
anode accelerates the electrons to a speed of 2.65 x 107 m/s. After this acceleration, the electrons pass through an opening in
the anode and enter the magnetic lens. The magnetic lens focuses the beam of electrons. A particular electron experiences a
magnetic force of 3.31 x 10-12 N while in the magnetic lens. As a result of this magnetic force, the path of the electrons spirals
and the beam of electrons becomes focused. Scanning coils deflect the beam of electrons back and forth across the specimen.
Some electrons from the beam reflect off the specimen at the same speed at which they hit. The backscattered electron detector
picks up these electrons. These backscattered electron provide information about the composition and surface characteristics
of the specimen.
3
PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS
The electron beam causes the specimen to emit electrons from its surface. The secondary electron detector picks up these
electrons. Information collected from the scanning coils and the two detectors is sent to the image processor. This processor
produces a three-dimensional image of the specimen.
11.
The magnitude of the magnetic field in the magnetic lens, expressed in scientific notation, is ________x 10-w T.
(Record your three-digit answer in the numerical-response section on the answer sheet.)
12. The instantaneous radius of the resulting spiral of the electron's path in the magnetic lens is
a.
5.17 x 103 m
b.
3.54 x 10-1 m
c.
1.93 x 10-4 m
13. The collision that produces a backscattered electron is classified
ii
in the kinetic energy of the system.
d.
i
7.29 x 10-12 m
as because there is
The statement above is completed by the information in row
a.
c.
i
elastic
inelastic
ii
a decrease
a decrease
b.
d.
i
elastic
inelastic
ii
no change
no change
Use the following additional information to answer the question.
The wavelength of an electron is modeled by the following formula,
In this formula,is the wavelength of the electron, h is Planck's constant, and is the momentum of the electron.
The higher the resolution of a microscope, the shorter the wavelength that it uses and the smaller the details it can distinguish.
A microscope, whether it uses light or a beam of electrons, has a resolution that is approximately 2 times the wavelength of the
wave used to examine the specimen.
4
PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS
14. The reason that electron microscopes have a higher resolution than visible-light microscopes is that electrons
have
a.
c.
mass
longer wavelengths than visible light
b.
d.
charge
shorter wavelengths than visible light
Use the following additional to answer the next two questions.
In the SEM, some of the electrons in the original beam knock electrons loose from lower energy levels of the atoms in the
specimen. An electron in a higher energy level of these atoms then makes a transition to fill the vacated lower energy level. The
following energy level diagram shows two possible electron transitions in lead.
15. The region of the electromagnetic spectrum in which the photons corresponding to the K and K lines for lead
are classified is most likely
a.
X-ray
b.
visible
c.
infrared
d.
microwave
16.
The frequency of the photons emitted in the K transition for lead, expressed in scientific notation, is ____x 10 w Hz.
(Record your three-digit answer in the numerical-response section on the answer sheet.)
5
PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS
Use the following additional information to answer the next three questions.
The original electron beam can knock loose valence electrons from the specimen. To detect these secondary electrons, a
scintillator and a photomultiplier tube are used.
Description of the Scintillator and a Photomultiplier Tube (PMT)
For each secondary electron that hits the scintillator, a photon that has a wavelength of 4.00 x 10-7 m is produced. This photon
hits the photocathode, which has a work function of 1.80 eV, and initiates an electron cascade, as illustrated below.
Inside the photomultiplier tube are several dynodes (intermediate anodes) and a final collector anode. Each dynode is kept at a
greater positive potential than the one previous to it. The electric potential difference between one dynode and the next is 150
VAn electron released from the photocathode is accelerated toward and collides with the first dynode, releasing a number of
tertiary electrons, which are in turn accelerated toward the next dynode. The process repeats with as much as a million- fold
increase in the number of electrons released by the time they reach the collector anode. This provides a strong electrical signal
in response to the detection of a single photon.
17. The process by which an electron is ejected from the photocathode in the PMT is
a.
c.
X-ray production
the Compton effect
b.
d.
radioactive decay
the photoelectric effect
18. The maximum kinetic energy of an electron ejected from the photocathode in this PMT is
a.
1.31 eV
b.
1.80 eV
c.
3.11 eV
d.
4.91 eV
e.
19. A particular electron, as it leaves one dynode, has a kinetic energy of 1.00 x 10 -17 J. The speed of this electron
when it reaches the next dynode will be:
a. 5.93 x 106 m/s
b. 7.26 x 106 m/s
c. 8.64 x 106 m/s
d. 1.32 x 107 m/s
20. Fission and fusion are two distinct types of nuclear reaction. Fusion can be described as a process in which
a.
b.
c.
d.
two low-mass nuclei combine to form a new nucleus with an atomic number greater than 26.
a nucleus with an atomic number less than 83 splits into smaller nuclei.
a nucleus with an atomic number greater than 83 splits into smaller nuclei.
two low-mass nuclei combine to form a new nucleus with an atomic number less than 26.
6
PHYSICS 30
MATTER ASSIGNMENT :1
VERSION:0
55 MARKS
145
21. Which one of the following isotopes is produced when 61 Pm decays by emitting an a particle?
a.
143 La
57
b.
c.
141 Pr
59
d.
145 Nd
60
e.
145 Pm
61
145 Sm
62
22. According to the Uranium Disintegration Series, how many different isotopes of polonium (Po) are formed as
decays to
a.
1
b.
2
c.
3
d.
0
23. In a nuclear reactor, one of the primary functions of the coolant is to
a.
c.
promote overheating in the reactor core
adjust the number of neutrons
b.
d.
transfer thermal energy to a heat exchanger
protect the reactor operators from radiation
24.
After a uranium nucleus emits an alpha particle, the total mass of the new nucleus and the alpha particle is less than the
mass of the original uranium nucleus. The steps for calculating the energy of the reaction are given below.
1) Use the formula E = mc2
2) Calculate the mass of the products and the mass of the reactants
3) Calculate the mass defect
4) Write a balanced nuclear equation for the reaction.
The correct chronological sequence for calculating the energy of the reaction is ____, ____, ____ and ____
25. A radioactive isotope has a half-life of 4.5 days. What fraction of the original sample will exist after 9.0 and 18.0
days respectively?
a.
and
b.
and
c.
and
d.
and
7