Download RTD Part 3 - County Central High School

!Numerical Respons~
1133.1 The magnitude of the magnetic field in the magnetic lens, expressed in scientific notation,
x 10-wT.
IS
(Record your three-digit answer in the numerical-response section on the answer sheet.)
134. The instantaneous radius of the resulting spiral of the electron's path in the magnetic lens is
A.
B.
C,
D.
7.29
X
1.93
x
10- 12 m
10-4m
3.54 X w-l m
5.17x10 3 m
135. The collision that produces a backscattered electron is classified as ---=--- because
there is
ii
in the kinetic energy of the system.
The statement above is completed by the information in row
Row
i
ii
A.
elastic
a decrease
B.
elastic
no change
c.
inelastic
a decrease
D.
inelastic
no change
Use the following additional information to answer the next two questions.
The wavelength of an electron is modeled by the following formula, hypothesized
by de Broglie.
In this formula, Ais the wavelength of the electron, h is Planck's constant, and p is
the momentum of the electron.
The higher the resolution of a microscope, 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.
-45-
136. The reason that electron microscopes have a higher resolution than visible-light microscopes is
that electrons have
A.
B.
C.
D.
mass
charge
longer wavelengths than visible light
shorter wavelengths than visible light
!Numerical Respons~
1137.1
In order to achieve an SEM resolution of 1.000 nm, the speed of the electrons, expressed in
scientific notation, should be a.bc x lOd m/s. The values of a, b, c, and dare _ _ , _ _ ,
___ ,and
(Record all four digits of your answer in the numerical-response section on the answer sheet)
Use the following additional information to answer !he 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.
Energy Level Diagram
M - - - - - - r - - - -9.91 eV
L
-22.0eV
K - - - " - - - - - - ' - - - -89.2 eV
IN umerical Respons~
IBS.j
The frequency of the photons emitted in the Ka transition for lead, ex pressed in scientific
x 10" Hz.
notation, is
(Record your three-digit answer in the numerical-response section on the answer sheet.)
-46-
139. The region of the electromagnetic spectrum in which the photons corresponding to the Ka
and K~ lines for lead are classified is most likely
A. X-ray
B. visible
C. infrared
D. microwave
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 a Scintillator and a Photomultiplier Tube (PMT)
For each secondary electron that hits the scintillator, a photon that has a wavelength
of 4.00 x I o- 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.
Photocathode
Scintillator
Ejected
Light electron
photon
(A
Electrons in
electron cascade
Focusing
Dynode
Photomultiplier tube (PM1)
electrode
=4.00 X 10-7 m)
Inside the photomultiplier tube are several dynodes (intennediate 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 V.
An electron released from the photocathode is accelerated toward and collides with
the first dynode, releasing a number of tertiary electrons, which are in tum
accelerated toward the next dynode. The process repeats with as much as a millionfold 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.
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140. The process by which an electron is ejected from the photocathode in the PMT is
A. X-ray production
B. radioactive decay
C. the Compton effect
D. the photoelectric effect
141. 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
142. A particular electron, as it leaves one dynode, has a kinetic energy of 1.00
of this electron when it reaches the next dynode will be
A. 5.93 x
B. 7.26 x
C. 8.64 x
D. 1.32 x
x
10- 17 J. The speed
106 m/s
106 m/s
106 m/s
107 m/s
Use the following information to answer the next three questions.
When a "LifeSavers™ WintOgreen" candy is crushed with pliers in a totally
darkened room, a flash ofblue light will be observed.
Before
After
LifeSavern.r
Pliers
Flash of blue light
[Numerical Respons~
1143.1
If the jaws of the pliers exert an average force on the LifeSavers TM candy of 8.50 x I 0 2 N
for 1.25 X 10- 1 s, then the impulse imparted to the LifeSavers™ candy, expressed in
scientific notation, is a.bc x 1Od N·s. The values of a, b, c, and dare _ _ , _ _ , _ _
and
(Record all four digits of your answer in the numerical-response section on the answer sheet)
-48-
Use the following additional information to answer the next question.
As the LifeSavers™ candy is crushed, electrons are released and collide with
nitrogen molecules in the air. These collisions cause the nitrogen molecules to
emit ultraviolet radiation.
144. The emission of an ultraviolet photon from a nitrogen molecule is a result of
A.
B.
C.
D.
radioactive decay in the nucleus
nuclear fusion of the absorbed electron
electron transitions from a higher energy level to a lower energy level
electron transitions from a lower energy level to a higher energy level
Use the following additional information to answer the next question.
The ultraviolet radiation emitted by the nitrogen molecules is absorbed by atoms
in the oil of wintergreen found in the LifeSavers™ candy. The atoms in the oil of
wintergreen immediately re-emit some of this energy as a flash of blue light.
!Numerical Respons~
lt4S.j
The atoms in the oil of wintergreen absorb ultraviolet radiation with a frequency of
8.50 x 10 14 Hz and re-emit blue light with a frequency of 7.50 x 10 14 Hz. The energy
difference in the conversion, expressed in scientific notation, is
x w-w J.
(Record your three-digit answer in the numerical-response section on the answer sheet.)
-49-
Use the following information to answer the next four questions.
To determine the electric force on a 2.5 x 10- 4 kg neutral pith ball, a student charges
a Van de Graaff generator and suspends the pith ball by an insulating thread.
I
I
Pith ball
I
Van de Graaff
generator
146. When the neutral pith ball is placed near the charged Van de Graaff generator, the pithball
is attracted to the generator as a result of
A. induction
B. grounding
C. conduction
D. induction and grounding
147. The direction of the electrical force on the pith ball is
A. i
B. l
c.D.
+---
148. The magnitude of the electrical force exerted on the pith ball by the charged Van de Graaff
generator is
A. 2.s x 1o- 3 N
B. 2.3 X 10- 3 N
c. 8.9 X 10- 4 N
D. 8.4 X 10- 4 N
-50-
Use the following additional information to answer the next question.
A student placed a piece of rabbit fur on the top of the sphere of the Van de Graaff
generator. The generator was then turned on and the rabbit fur was repelled and
formed an arc directly above the generator. When the generator was turned off, the
fur remained in the same position.
Using a camera with a flash, a second student then took a picture of the apparatus.
Immediately after the flash, the fur collapsed somewhat.
149. The concept that explains the collapse of the rabbit fur is
A. induction
B. grounding
C. conduction
D. the photoelectric effect
150. A stream of electrons with a given speed, v, enters a magnetic field of known intensity, B.
The direction of the motion of the electrons is perpendicular to the direction of the
magnetic field. Changes are made to both Band v. The radius of the circular path of the
electrons will always increase when
A.
B.
C.
D.
B increases and v increases
B increases and v decreases
B decreases and v increases
B decreases and v decreases
-51 -
Use the following information to answer the next seven questions.
The Deep Space 1 mission (DS 1) uses a ion propulsion system (IPS) on the DS 1
capsule. The IPS involves ionizing atoms of xenon, accelerating them through an
electric field produced by electrified grids, and ejecting the ions into space behind
the capsule.
IPS Chamber of the DSl Capsule
Electrified grids
Electron gun
(produces highspeed electrons)
•Xe
·ll-
D
D
D
•
D
D
D
D
Xe
D
D
:xe+D
•
D
D
•Xe
Positive a
D
grid
D
D
D
D
aNegative
Dgrid
In the IPS chamber, high-speed electrons collide with xenon atoms. These
collisions can ionize xenon atoms. The electric field then accelerates the ions and
ejects them from the IPS chamber, which propels the DS I capsule forward.
IPS Operating Specifications for DSl
propellant ions
total mass of propellant
mass ofDS1 capsule (without propellant)
energy required to ionize a xenon atom
mass of a single xenon atom
exit speed of xenon ions
Xe+
81.5 kg
489.5 kg
12.1 eV
2.18 X 10-2S kg
43.0 krn/s
151. The minimum electron speed necessary to ionize xenon atoms is
A.
B.
C.
D.
2.66 x 1031 m/s
5.15 x 10 15 m/s
4.25 x 10 12 m/s
2.06 x I 06 m/s
-52-
152. The electric potential difference across the electrified grids that is required to accelerate a
xenon ion from rest to its exit speed is
A. 2.93 X 10-5 v
B. 1.26 X 10-3 V
C. 1.26 X 10 3 V
D.4.7Ixi0 29 V
153. If all of the xenon propellant could be expelled in a single short burst, the change in the
speed of the DS I capsule after all the fuel has been exhausted would be
A. 6.14m/s
B. 7.16 m/s
C. 6.14 x 10 3 m/s
D. 7.16 x 103 m/s
154. The physics principle that best describes the propulsion of the DSI capsule is the Law of
Conservation of
A.
B.
C.
D.
Charge
Energy
Momentum
Nucleon Number
!Numerical Respons~
1155.1 As xenon ions in the exhaust stream behind the DS I capsule interact with other charged
particles in space, the xenon ions become neutral atoms, and in the process, emit photons.
The maximum frequency of these photons, expressed in scientific notation, is
x 10"' Hz.
----(Record your three-digit answer in the numerical-response section on the answer sheet)
Use the following additional information to answer the next two questions.
One isotope of xenon, xenon-133, is an unstable isotope that undergoes beta negative
decay and has a half-life of 5.24 days.
!Numerical Respons~
jl56.j If the IPS uses 81.5 kg of xenon-133 as a propellant and the launch is delayed by 26.2 days,
the amount of xenon-133 that would remain is
kg.
(Record your three-digit answer in the numerical-response section on the answer sheet)
-53 -
157. The decay equation for xenon-133 is
A. ~~~Xe ~ ~;~xe + r
B.
c.
158. Ions, each having a single charge, are accelerated to a given speed. They then enter a
magnetic field in a direction perpendicular to the field. The radius of the curved path of
each ion is measured. The graph that best shows the relationship between the mass of an
ion and the radius of its path is
A.
B.
r
r
m
m
c.
D.
r~
r~
m
m
Use thefol/mving information to answer the next three questions.
An experiment is designed to study the charge-to-mass ratio of hydrogen ions.
Hydrogen ions, all moving in the same direction and with the same speed, v, are
injected into a mass spectrometer. The magnitude of the magnetic field is varied,
and the resulting radii of the path of the hydrogen ions are measured.
159. The equation that describes the radius of curvature of an ion's path is
qB
A. r = -
B.
c.
mv
mv
r=qB
qv
r=-
mB
mB
D. r =qv
-54-
160. A graph that shows the relationship between the radius of curvature of a hydrogen ion's
path and the strength of the magnetic field is graph
A.
B.
r
r
B
B
c.
D.
B
B
Use the following additional information to answer the next question.
The manipulated variable in this experiment was modified in order to obtain the
straight line graph shown below. The slope of this straight line graph can be used to
determine the charge to mass ratio of a hydrogen ion.
r
161. Which of the following expressions gives the correct value for the charge to mass ratio?
A.
B.
C.
D.
slope squared times speed
slope divided by speed
speed divided by slope
speed times slope
-55-
162. Experiments with cathode ray tubes led to the discovery of the
A.
B.
C.
D.
photon
neutron
electron
alpha particle
163. J. J. Thomson's experiments indicated that cathode rays are
A.
B.
C.
D.
photons
electromagnetic radiation
positively charged particles
negatively charged particles
164. Which of the following conclusions most closely followed the discovery that cathode rays
consist of charged particles?
A. J.J. Thomson's conclusion that all atoms contain smaller parts called electrons
B. Bohr's conclusion that electrons inhabit discrete energy levels around the nucleus
C. Maxwell's conclusion that accelerating charges produce electromagnetic radiation
D. Rutherford's conclusion that the atom has a dense, positively charged nucleus that
electrons orbit
165. If the charge-to-mass ratio of an ion with a 3+ charge is 1.4
the ion is
A.
B.
C.
D.
1.1
3.4
J.O
6.7
X
X
X
X
x
10 7 C/kg, then the mass of
10-26 kg
10-26 kg
10-2S kg
10- 12 kg
166. An oil drop ofmass 6.6 x 10- 14 kg is suspended in an electric field of2.0 x 10 6 N/C
between horizontal plates that are 4.0 x 10-2 m apart. The number of excess electrons on
the oil drop is
A. 1
B. 2
c.
5
D. 20
-56-
Use the following information to answer the next question.
Observation
The value of q/m for a cathode-ray particle is about 1800 times greater than the value of qlm for a
hydrogen ion.
Conclusions That May Be Supported by the Observation
I
The charge on a cathode-ray particle is 1800 times greater than the charge on a hydrogen ion.
II
The charge on a cathode-ray particle is -
1-
1800
of the charge on a hydrogen ion.
III The mass of a cathode-ray particle is 1800 times greater than the mass of a hydrogen ion.
IV The mass of a cathode-ray particle is -
1-
1800
of the mass of a hydrogen ion.
167. The observation supports conclusions
A.
B.
C.
D.
I and III
land N
II and III
II and IV
168. The charge and the approximate diameter of a nucleus may be estimated from
A. cathode-ray experiments
B. photoelectron experiments
C. X-ray diffraction experiments
D. alpha particle scattering experiments
169. In certain scattering experiments, alpha particles bounce backward from a thin metal target.
This observation led to the hypothesis that
A.
B.
C.
D.
alpha particles carry electric charges
charge is uniformly distributed throughout the atom
alpha particles' kinetic energy cannot be converted to potential energy
the centre of the atom is very small, charged, and contains most of the atom's mass
-57-
Use the following information to answer the next three questions.
Side View of the Components of an Ink-Jet Printer
The essential components of one type of ink-jet printer are shown below.
Ink drops
~
,-'-"--<XX>---
n
LJ
Charging
elect:t':od~
Ink drop
generator
Det1ection
plates
Ink drops from the generator pass through a charging electrode. By means of a
signal from a computer, the charging electrode controls the charge given to the ink
drops. Ink drops are deflected between the deflection plates. The deflection plates
are 0.100 mm apart, and there is a potential difference of 120 V across them. The
amount each drop is deflected determines where it strikes the paper. A typical ink
drop has a mass of 1.32 x 1o- 10 kg. Approximately 100 ink drops are needed to
form a single letter on paper.
Ink drop I 1 has a charge of -1.51 x 10- 13 C.
!Numerical Respons~
lt70.I The number of excess electrons given to ink drop /
1, expressed in scientific notation, is
a.bc x 1Od electrons. The values of a, b, c, and dare~-' _ _ , _ _ , and _ _ .
(Record all four digits of your answer in the numerical-response section on the answer sheet)
171. As the charged ink drop, I 1, moves through the deflection plates, it experiences an electric
force with a magnitude of
A. 1.81
B. 1.81
c. 1.81
D. 1.81
X
X
X
X
10- 15 N
10- 12 N
10-IO N
10-7 N
-58 -
172. To cause ink drop h to follow the path shown, the direction of the electric field between
the charged deflection plates must be toward the
A.
B.
C.
D.
bottom of the page
right of the page
left of the page
top of the page
Use the following information to answer the next question.
To demonstrate the development of Rutherford's atomic model, a teacher lined up five
students at arm's length from each other. She then tossed bean bags toward them. Most of the
bean bags went past the line of students without coming into contact with any of them.
Occasionally, a bean bag would hit a student and the bean bag would drop to the floor.
173. In this demonstration, the bean bags and the students represent, respectively,
A.
B.
C.
D.
alpha particles and electrons
electrons and alpha particles
nuclei and alpha particles
alpha particles and nuclei
Use the following information to answer the next question.
Selected Levels of a Mercury Atom
Level
Energy (eV)
0
•
z
y
X
w
-1.6
-3.7
-5.5
-10.4
174. What frequency of electromagnetic radiation is required to excite mercury atoms from
energy level W to energy level Z?
A. 2.1 x 10 15 Hz
B. 2.5 x 10 15 Hz
C. 2.9 x 10 15 Hz
D. 3.1 x 10 15 Hz
-59-
Use the following information to answer the next question.
Energy Levels for Mercury Atoms (eV)
OeV ---------------
-1.6 eV - - - - - - - - - - - -
-3.7 eV - - - - - - - - - - - - -
-5.5 eV - - - - - - - - - - - - -
-10.4eV - - - - - - -
175. If an electron is in the -1.6 e V energy level, the minimum frequency of a photon that
would ionize the atom is
A.
B.
C.
D.
3.9 x
2.1 x
2.4 x
1.3 x
10 14 Hz
10 15 Hz
10 33 Hz
10 34 Hz
176. The element 2 ~~U undergoes radioactive decay until it attains a stable state as zg~Pb. The
first four stages of this decay series are
2 ~~U
~
2 ~~Th
~
2 ~{Pa
~
2 ~!U
~
2 ~8Th.
The particles emitted in each of these steps are, respectively,
A.
B.
C.
D.
alpha, beta, beta, alpha
beta, alpha, alpha, beta
alpha, gamma, gamma, alpha
gamma, alpha, alpha, gamma
- 60-
Use the following information to answer the next question.
Energy Levels of a Hypothetical Atom
n = oo
n=4
O.OeV
-1.6eV
n=3
-3.7 eV
n=2
-5.5 eV
n=l
-10.4 eV
!Numerical Respons~
ltn.l The energy required to ionize this atom when the electron is in the second energy level is
_ _ _ _ _ eV.
(Record your two-digit answer in the numerical-response section on the answer sheet.)
178. In a nuclear reaction, the mass of the products was determined to be considerably less than
the mass of the reactants. A correct explanation of this is that
A.
B.
C.
D.
the reaction was a beta-decay
a large amount of energy was released in the reaction
the mass of the alpha and beta particles was not accounted for
a large amount of energy was required to cause the reaction to occur
- 61 -
Use the following information to answer the next question.
A computer monitor displays the relative intensities of two emission lines of the helium
•
spectrum, as shown below.
S87.6nm
·~
I
388.8nm
a
....=
Cl.l
-!tiS
~
Wavelength
179. The difference in energy associated with the photons from the two lines of the helium
spectrum is
A.
B.
C.
D.
1.60 X
1.73 X
4.07 X
8.14 X
10- 19 ]
10- 19 ]
10- 19 J
10- 19 ]
180. An experiment starts with 1.45 kg of iodine-131. After 32.2 days, 90.6 g are left. The halflife of iodine-131 is
A.
B.
C.
D.
32.2 days
16.1 days
8.05 days
4.04 days
181. The half-life of radium-226 is 1.6
radium-226 to decay to 2.50 mg?
A.
B.
C.
D.
1.3
1.6
3.2
4.8
x
I 03 years. How long will it take for 20.0 mg of
103 years
x 103 years
x 103 years
x 103 years
x
- 62-
Use the following information to answer the next question.
In December 1994, research physicists in Darmstadt, Germany, announced that they
had detected three atoms of a new element. With 111 protons and 161 neutrons,
this lab-made element had the highest atomic number known to that date. To create
element 111, the physicists bombarded bismuth atoms, which have 83 protons, with
a beam of nickel atoms, which contain 28 protons. Signals ofthe three atoms of
element 111 appeared for less than two-thousandths of a second. The atoms then
decayed into lighter elements and alpha particles. One of the isotopes produced in
the decay was element 107 with a mass number of 264. This isotope had never
previously been observed.
Note: Because neither element 111 nor element 107 had been officially named,
element 111 was referred to as X and element 107 was referred to as Y.
182. The overall nuclear equation for this decay reaction is
+ 2 4He
2
264y + 2 4He
107
2
A.
161x
111
264y
---+ 107
B.
272x
111
---+
c.
161x
111
---+ ig~Y
D.
272x
111
---+
+ 21He
~gjY + ~Be
- 63-
Use the following information to answer the next three questions.
Carbon Dating Using a Mass Spectrometer
One method of determining the age of archeological remains is carbon dating. Of all
carbon isotopes present in living tissue, 1.66 x 10- 10 % is carbon-14. The radioactive
half-life of carbon-14 is 5. 73 x 10 3 years. A mass spectrometer is a device that separates
ions of different masses and can be used to determine the percentage of carbon-14
present in a sample.
In a mass spectrometer, a source produces gaseous ions that are accelerated by two
vertical parallel plates that have a large potential difference between them. The beam of
ions enters a velocity selector that allows only those ions with a specific velocity to pass
through undeflected. Finally, the ions enter a magnetic field B2 where the ions are
separated according to their mass.
Ion separation region
0
Indicates B1 and B2 directed perpendicularly out of the page.
A leather sandal from an archeological find is analyzed in order to determine the age of
the sandal.
183. In the leather sandal, the mass spectrometer measures the carbon-14 content as
8.30 x 10- 11 % of all carbon isotopes present. The approximate age of the sandal is
A.
B.
C.
D.
1.43 x I 0 3 years
5.73 x I 0 3 years
1.15 x I 04 years
2.29 x 104 years
- 64-
!Numerical Respons~
lt84.1 The carbon atoms in the sandal are ionized by high-energy photons in the source chamber
of the mass spectrometer. The ionization energy of carbon is 11.3 eV. The minimum
frequency of radiation required in the source, expressed in scientific notation, is
X lOwHz.
---(Record your three-digit answer in the numerical-response section on the answer sheet.)
185. The horizontal speed of the stream of carbon ions through the velocity selector is given by
the expression
C.
mgd
q
D.
R
- 65-
Use the following information to answer the next three questions.
Smoke Alarm
.
Radioactive
somceofa:
particles
.-
--- *
---.....
- . - --·· ---- e
-~~=:~~~~-------------------
1
+
-._ -------.____ .. ..... -e__..
.....
... ... ...
*
...
"'---. --
......_E!)._--
---
To the alann, which
will sound when the
current drops too low
Very high
resistance
-
........_®--.
-. .
/
'
Ventilated outer case
-Ionized air molecules maintain a current
Half-Life of Selected Isotopes
Element
hydrogen
carbon
iodine
lead
polonium
polonium
urannun
m·anmnl
uramtun
plutonium
plutonimn
Isotope
3H
Half-life
Radiation pi'oduced
12.3 a
B
6c
5715 a
B
~~;I
8.04 d
B
-s2Pb
194
84Po
210p
10.6 h
B
0.7 s
a
138 d
a
221u
1.1 min
a
92
7.04 x 108 a
a
nsu
92
4.46 x 109 a
a
2.87 a
a
3.76 x 10 5 a
a
1
14
">l'J
84
0
92 '
-:>r
_)u
236
94Pu
J47
-94Pu
Legend: a
= munun = year
- 66-
186. Given the specifications of this smoke alarm, which of the following isotopes could be used
as a radioactive source?
A.
iH
B. 1~c
c. 194p
84 0
D. 2 ~~Pu
187. The product of the alpha decay of 2 ~~U is
A. z~6Th
B.
2 ~~Th
z3zu
92
D. 234u
90
c.
!Numerical Respons~
l188.l Tritium (iH), an isotope ofhydrogen, was once used in some watches to produce a
fluorescent glow. Assuming that the brightness of the glow is proportional to the amount
of tritium present, the length of time it would take for the watch to reach ~ of its original
4
brightness is
years.
(Record your three-digit answer in the numerical-response section on the answer sheet.)
- 67-
Use the following information to answer the next two questions.
As artificial elements are created, they are added to the periodic table. In 1982, the
I 091h element, unnilennium, was created. It was found that unnilennium emits alpha
particles as it decays.
Radioactive Decay of Unnilennium
10
l).fi
5
5
9
8
7
·-==- 6
..:: 5
·-·
=
.-..
...
:....;;
=
"'::!:'ll
~
~
4
3
2
1
0
0
1
2
4
3
5
6
7
Timt> (ms)
189. The nuclear equation describing this decay is
A. ig~Une
~
B. 266Une
109
~
c.
266Une
109
~
D. ig~Une
~
ig~uns
+ ~He
266u n d + -1e
o
110
ig~une + y
265Uno + lH
108
1
190. As determined from the graph, the half-life of unnilennium is between
A.
B.
C.
D.
I ms and 2 ms
2 ms and 3 ms
3 ms and 4 ms
4 ms and 5 ms
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8
Use the following information to answer the next three questions.
A scientist places a 10 g sample of 224Ra, which has a half-life of3.66 d, into a
shielded box that allows a stream of high energy particles to escape. The scientist
then applies a potential difference of 5.3 x 105 V across horizontal plates that are
3.0 x 10- 1 m apart and a perpendicular magnetic field of0.70 T. She observes that
the particle beam passes through the apparatus undeflected. When the electric field
is eliminated, the magnetic field causes the particles to orbit in a circle with a radius
of7.5 x 10-2 m.
Note: The entire apparatus is in a vacuum.
---Coils that produce a
uniform magnetic field
191. The mass of 224Ra remaining after 22 days is
A. 0.16g
B. 0.31 g
c. 2.7 g
D. 3.7 g
!Numerical Respons~
1192.1 The particles in the undeflected beam are moving at a speed of a.b
of a, b, and c, are, respectively, _ _ , _ _ , and _ _ .
x
lOc m/s. The values
(Record all three digits of your answer in the numerical-response section on the answer sheet)
193. Using the charge-to-mass ratio of the particles, the scientist determines the particles to be
A. protons
B. neutrons
C. electrons
D. alpha particles
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Use the following information to answer the next two questions.
Mass spectrometers are used in archeological studies to help date ancient artifacts. The
relative amounts of carbon-12 and carbon-14 isotopes in a sample of organic material
may be used to determine the age of the sample. Carbon-14 is a radioactive isotope that
undergoes beta negative decay and has a half-life of 5 730 years.
194. The product of the carbon-14 decay is
A. ljN
B. 1~0
c.
1 ~Be
D. l~c
195. An archeological sample is dated using the carbon-14 dating process and is found to be
2 865 years old. What percentage of the original carbon-14 remains?
A. 25.0%
B. 29.3%
c. 70.7%
D. 75.0%
Use the following information to answer the next question.
A student obtains samples of pure quantities oftwo radioactive isotopes: X andY. The
samples contain equal numbers of atoms. The half-life of each isotope is given below.
Half-life of radioactive isotope X:
Half-life of radioactive isotope Y:
120 days
15.2 days
Both isotopes undergo beta decay.
196. Which of the following situations would result in a person experiencing the most exposure
to radioactivity?
A.
B.
C.
D.
Being exposed to isotope X at a distance of one metre for two hours
Being exposed to isotope Y at a distance of one metre for two hours
Being exposed to isotope Y at a distance of two metres for two hours
Being exposed to isotope X at a distance of two metres for t\vo hours
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