Physics 228 Final MAY 12, 2009 Profs. Rabe and Coleman. Useful Information. Your name sticker. with exam code

Transcription

1 Your name sticker with eam code Physics 228 Final MAY 12, 2009 Profs. Rabe and Coleman guess. At the end of the eam, hand in the answer sheet and the cover page. Retain this question paper for future reference and study. 8. When you are asked to open the eam, make sure that your copy contains all 30 questions. Raise your hand if this is not the case, and a proctor will help you. Also raise your hand during the eam if you have a question. 9. Please SIGN the cover sheet under your name sticker. A proctor will check your name sticker and your student ID sometime during the eam. Please have them ready. SIGNATURE: TURN OFF CELLPHONES NOW!!! 10. Good luck! Useful Information 1. The eam will last from 4:00 p.m. to 7:00 p.m. Use a #2 pencil to make entries on the answer sheet. Enter the following ID information now, before the eam starts. 2. 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. 3. Under STUDENT # enter your 9-digit Identification Number. 4. Enter 228 under COURSE, and your section number (see label above) under SEC. 5. Under CODE enter the eam code given above. 6. During the eam, you may use pencils, a calculator, and three handwritten inch sheets with formulas and notes, without attachments. 7. There are 30 multiple-choice questions on the eam. 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 c = speed of light = m/s q e = e = charge on an electron = Coulombs q p = +e = charge on a proton = Coulombs k e = N m 2 /C 2 N A = Avogadro s number = particles/mol k B = Boltzmann s constant = J/K Wien s Constant = m K σ = Stefan s Constant = W/(m 2 K 4 ) h = J-s h = ev-s (in units of electron volts-second) h = h = π Js hc = 1240 ev nm = 1240 MeV fm 1 ev = J 1 kev = 1000 ev µ B = Bohr Magneton = ev/t = J/T g-factor of electron = u = 1 atomic mass unit = MeV/c 2 m e = electron mass = kg m e c 2 = electron rest energy = MeV m p = proton mass = kg m p c 2 = proton rest energy = MeV m n c 2 = neutron rest energy = MeV m π ±c 2 = charged pion rest energy = MeV

2 m π 0c 2 = neutral pion rest energy = MeV M( 1 1H) = u 1rad = 0.01 J/Kg RBE = Relative Biological Effectiveness Temperature conversion: T (K) = T ( C) = 1.8 T ( F) Zeroes of temperature scale: K = 0 C =32 F 1 nm = 10 9 m 1 Å = m = 0.1 nm 1 µm = 10 6 m 1 mhz = 10 3 Hz 1 khz = Hz 1 MHz = Hz 1 GHz = Hz Some quantum numbers: Q/e B S u 2/3 1/3 0 d 1/3 1/3 0 s 1/3 1/3-1 L e L µ L τ e, ν e µ, ν µ τ, ν τ 0 0 1

3 1. Which of the following statements about the Standard Model of particle physics is false? a) Strangeness is not conserved by the weak interaction. b) Hadrons are bound states of quarks, or antiquarks. c) Bosons are the matter constituents. Fermions mediate the forces between particles. d) The weak force is short-ranged because of the large mass of the Z and W particles. e) There are three known generations of leptons. 2. The Ξ particle has the following properties: B = 1, S = 2, Q = 1. Which of the following is a possible quark combination for Ξ? a) c s s b) uds c) s s d) uss e) dss 3. The threshold frequency for photoemission in silver is Hz. For what frequency will the photoelectric stopping potential be 1.36 V? a) Hz b) Hz c) Hz d) Hz e) Hz 4. The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. The inde of refraction of the liquid is: a) 1.50 b) 1.67 c) 1.75 d) 1.25 e) 1.33 "Hairy Eyeball" 5. A photon, an electron, and a baseball have the same momentum. Which has the largest de Broglie wavelength? a) baseball and electron b) all have the same wavelength c) electron d) photon e) baseball 6. A K α X-ray emitted from a sample has an energy of 4.08keV. What is the atomic number of the element producing this X-ray? a) 401 b) 21 c) 19 d) 400 e) 20 4 ft E 3 ft 7. When a nonrelativistic beam of electrons is focused down to a diameter, it is found that the electrons velocities perpendicular to the beam can be measured to a precision of v e. If a nonrelativistic beam of protons is focused to the same diameter, the protons perpendicular velocities can be determined to a precision of about v p = a) 10 v e b) e) v e v e 2000 c) 2000 v e d) 1 2 v e

4 8. In a Young s double-slit eperiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen that is 5 m from the slits is: a) 0.50 cm b) 1.0 cm c) none of the other answers d) 0.10 cm e) 0.25 cm 9. A diffraction grating of total width 4 cm is illuminated with light of wavelength 577 nm. The second-order principal maimum is formed at an angle of What is the total number of lines (slits) in the grating? a) About b) About 5000 c) About d) About 8000 e) About Two electrons with opposite spin are in an l = 0 orbital. A magnetic field of 1 T is present. What is the energy separation between the two electron levels? a) ev b) ev c) ev d) ev e) ev 11. At room temperature (T = 300K), the occupation probability of an electron state in the valence band of Zn with kinetic energy 10% greater than the Fermi energy (E F = ev) is about: a) 0.94 b) c) d) 0.11 e) A diatomic molecule is in a vibrational and rotational state having energy 0.50 ev when it absorbs a photon of frequency Hz. What is the energy of the final state of the molecule? a) 0.56eV b) 0.90eV c) 0.10eV d) 0.43eV e) 0.50eV 13. For a diatomic molecule, it is found that the rotational states l=0 and l=1 are separated in energy by ev. The moment of inertia of the molecule is: a) kg m 2 b) not enough information. c) kg m 2 d) kg m 2 e) kg m If you were in a spaceship traveling at a constant speed close to the speed of light (with respect to earth), you might make the following observations: (I)That some of your physical dimensions were reduced. (II)That your mass was greatly increased. (III)That your pulse rate is a lot slower due to time dilation. Which of these observations could actually take place? a) None of these effects would occur. b) More than one of these effects would occur. c) (III) d) (I) e) (II)

5 15. A particle in a bo of length L is in the n = 3 state. Which diagram in the figure best describes its probability distribution? 18. An atom with N electrons will be chemically inert if N=: a) 5 b) 25 c) 20 d) 10 e) 15 a) III b) I c) II d) V e) IV (I) (III) (V) (II) (IV) 19. A concave mirror forms a real image which is twice the size of the object, but inverted. If the object is 20 cm from the mirror, the focal length of the mirror must be about: a) 27 cm b) 13 cm c) 40 cm d) 10 cm e) 20 cm 20. An object placed in front of a thin lens of focal length +5 cm produces an image 10 cm from the lens on the same side as the object. How far is the object from the lens? a) 20 cm b) 10 cm c) 5 cm d) 2.8 cm e) 3.3 cm 16. The average person receives a dose of 102 m rem/year. If the average RBE of the radiation received is 1.5, how much energy, in Joules, is absorbed per year by a 70 kg person? a) b) 4.76 c) d) 7.14 e) K-mesons have an average proper lifetime τ. How fast must they move with respect to the earth so that an earth-based eperimenter will measure an average lifetime of 1.5 τ? a) 0.75c b) 0.40c c) 0.90c d) 0.50c e) 0.80c

6 21. In the energy level diagrams shown, the shaded region represents the occupied electron states beneath the Fermi energy. The white regions represent the empty electron states. Which answer best describes solids (I), (II), and (III)? a) (I) insulator, (II) metal, (III) semiconductor b) (I) semiconductor, (II) metal, (III) insulator c) (I) metal, (II) metal, (III) semiconductor d) (I) insulator, (II) metal, (III) metal e) (I) metal, (II) insulator, (III) semiconductor I II III conduction band valence band 22. The following rest energies are known: m e c 2 = electron rest energy = MeV m p c 2 m n c 2 m π ±c 2 m π 0c 2 = proton rest energy = MeV = neutron rest energy = MeV = charged pion rest energy = 139.6MeV = neutral pion rest energy = 135.0MeV A few months from now, the Large Hadron Collider (LHC) at CERN in Geneva will be operating. Suppose that a head-on collision between protons and antiprotons, each having a kinetic energy of 1700 MeV, produces the reaction p + p π + + π + H where H is the newly discovered Higgs particle. The Higgs is at rest and the π + and π depart in opposite directions, each with a kinetic energy of 110 MeV. What is the rest mass of the Higgs? a) 2388 MeV/c 2 b) 4777 MeV/c 2 c) 658 MeV/c 2 d) 1420 MeV/c 2 e) 3180 MeV/c Consider the decay sequence shown. Which of the following correctly identifies nucleus Y? 209 a) 83 Bi 208 b) 81 Tl 210 c) 82 Pb 202 d) 80 Hg 212 e) 84 Po 216 Po 84 α 212 Pb 82 β 212 Bi 83 β Y α α X β Pb

7 24. In the Bohr model of the hydrogen atom, which of the following transitions emits a photon with the longest wavelength? a) n=4 n=2 b) n=6 n=7 c) n=2 n=1 d) n=6 n=5 e) n=5 n=3 25. A radioactive source consists of atoms. It is observed that atoms decay per second. What is the half-life of the radioactive material? a) 2200 years b) 3200 years c) 1740 years d) 1520 years e) years 26. Protons are accelerated in a cyclotron with an internal field of 0.2 T. If beam eits at a radius of 2 m from the center of the cyclotron, what is the energy of the protons? a) 15.3 MeV b) 14 GeV c) 38.3 MeV d) 7.67 MeV e) 1.92 MeV 27. A perfectly black body at C emits light of intensity I. The temperature of this body is now raised to C. The hotter black body now radiates light of intensity closest to: a) 2.0 I b) 8.0 I c) 1.4 I d) 2.6 I e) 4.0 I 28. Suppose the ratio of the density of free electrons in aluminum to to that in potassium is 3:1. If the Fermi energy in potassium is 1.3eV what is the Fermi energy in aluminum? a) 1.9 ev b) 2.7 ev c) 11.7 ev d) 6.7 ev e) 3.9 ev 29. The following masses are known: 1 0n u 1 1 H u 7 3Li u. Given this information, the binding energy of 7 3Li, in MeV, is epected to be closest to: a) 39 b) 56 c) 52 d) 48 e) In the diffraction pattern from a si slit diffraction grating, which phasor diagram represents the combination of electric fields from the si slits when the path length difference between light from neighboring slits is a third of a wavelength? a) II b) IV c) III d) I e) V (I) (IV) (II) (V) (III)

8 Your name sticker with eam code Physics 228 Final MAY 12, 2009 Profs. Rabe and Coleman guess. At the end of the eam, hand in the answer sheet and the cover page. Retain this question paper for future reference and study. 8. When you are asked to open the eam, make sure that your copy contains all 30 questions. Raise your hand if this is not the case, and a proctor will help you. Also raise your hand during the eam if you have a question. 9. Please SIGN the cover sheet under your name sticker. A proctor will check your name sticker and your student ID sometime during the eam. Please have them ready. SIGNATURE: TURN OFF CELLPHONES NOW!!! 10. Good luck! Useful Information 1. The eam will last from 4:00 p.m. to 7:00 p.m. Use a #2 pencil to make entries on the answer sheet. Enter the following ID information now, before the eam starts. 2. 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. 3. Under STUDENT # enter your 9-digit Identification Number. 4. Enter 228 under COURSE, and your section number (see label above) under SEC. 5. Under CODE enter the eam code given above. 6. During the eam, you may use pencils, a calculator, and three handwritten inch sheets with formulas and notes, without attachments. 7. There are 30 multiple-choice questions on the eam. 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 c = speed of light = m/s q e = e = charge on an electron = Coulombs q p = +e = charge on a proton = Coulombs k e = N m 2 /C 2 N A = Avogadro s number = particles/mol k B = Boltzmann s constant = J/K Wien s Constant = m K σ = Stefan s Constant = W/(m 2 K 4 ) h = J-s h = ev-s (in units of electron volts-second) h = h = π Js hc = 1240 ev nm = 1240 MeV fm 1 ev = J 1 kev = 1000 ev µ B = Bohr Magneton = ev/t = J/T g-factor of electron = u = 1 atomic mass unit = MeV/c 2 m e = electron mass = kg m e c 2 = electron rest energy = MeV m p = proton mass = kg m p c 2 = proton rest energy = MeV m n c 2 = neutron rest energy = MeV m π ±c 2 = charged pion rest energy = MeV

9 m π 0c 2 = neutral pion rest energy = MeV M( 1 1H) = u 1rad = 0.01 J/Kg RBE = Relative Biological Effectiveness Temperature conversion: T (K) = T ( C) = 1.8 T ( F) Zeroes of temperature scale: K = 0 C =32 F 1 nm = 10 9 m 1 Å = m = 0.1 nm 1 µm = 10 6 m 1 mhz = 10 3 Hz 1 khz = Hz 1 MHz = Hz 1 GHz = Hz Some quantum numbers: Q/e B S u 2/3 1/3 0 d 1/3 1/3 0 s 1/3 1/3-1 L e L µ L τ e, ν e µ, ν µ τ, ν τ 0 0 1

10 1. For a diatomic molecule, it is found that the rotational states l=0 and l=1 are separated in energy by ev. The moment of inertia of the molecule is: a) not enough information. b) kg m 2 c) kg m 2 d) kg m 2 e) kg m 2 4. Consider the decay sequence shown. Which of the following correctly identifies nucleus Y? 209 a) 83 Bi 212 b) 84 Po 202 c) 80 Hg 208 d) 81 Tl 210 e) 82 Pb 216 Po 84 α 212 Pb 82 β 212 Bi 83 β Y α α X β Pb 2. A particle in a bo of length L is in the n = 3 state. Which diagram in the figure best describes its probability distribution? a) IV b) V c) II d) I e) III (I) (III) (V) (II) (IV) 3. In a Young s double-slit eperiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen that is 5 m from the slits is: a) 0.10 cm b) 1.0 cm c) none of the other answers d) 0.25 cm e) 0.50 cm 5. The following rest energies are known: m e c 2 = electron rest energy = MeV m p c 2 m n c 2 m π ±c 2 m π 0c 2 = proton rest energy = MeV = neutron rest energy = MeV = charged pion rest energy = 139.6MeV = neutral pion rest energy = 135.0MeV A few months from now, the Large Hadron Collider (LHC) at CERN in Geneva will be operating. Suppose that a head-on collision between protons and antiprotons, each having a kinetic energy of 1700 MeV, produces the reaction p + p π + + π + H where H is the newly discovered Higgs particle. The Higgs is at rest and the π + and π depart in opposite directions, each with a kinetic energy of 110 MeV. What is the rest mass of the Higgs? a) 658 MeV/c 2 b) 1420 MeV/c 2 c) 2388 MeV/c 2 d) 3180 MeV/c 2 e) 4777 MeV/c 2

11 6. The following masses are known: 1 0 n u 1 1H u 7 3 Li u. Given this information, the binding energy of 7 3Li, in MeV, is epected to be closest to: a) 43 b) 39 c) 52 d) 48 e) When a nonrelativistic beam of electrons is focused down to a diameter, it is found that the electrons velocities perpendicular to the beam can be measured to a precision of v e. If a nonrelativistic beam of protons is focused to the same diameter, the protons perpendicular velocities can be determined to a precision of about v p = v a) e 1 e) v 2 e 2000 b) v e c) 10 v e d) 2000 v e 8. In the diffraction pattern from a si slit diffraction grating, which phasor diagram represents the combination of electric fields from the si slits when the path length difference between light from neighboring slits is a third of a wavelength? a) I b) IV c) V d) III e) II (I) (IV) (II) (V) (III) 9. A diffraction grating of total width 4 cm is illuminated with light of wavelength 577 nm. The second-order principal maimum is formed at an angle of What is the total number of lines (slits) in the grating? a) About b) About 5000 c) About d) About e) About A concave mirror forms a real image which is twice the size of the object, but inverted. If the object is 20 cm from the mirror, the focal length of the mirror must be about: a) 27 cm b) 40 cm c) 13 cm d) 10 cm e) 20 cm 11. The threshold frequency for photoemission in silver is Hz. For what frequency will the photoelectric stopping potential be 1.36 V? a) Hz b) Hz c) Hz d) Hz e) Hz 12. Protons are accelerated in a cyclotron with an internal field of 0.2 T. If beam eits at a radius of 2 m from the center of the cyclotron, what is the energy of the protons? a) 1.92 MeV b) 38.3 MeV c) 7.67 MeV d) 14 GeV e) 15.3 MeV

12 13. A diatomic molecule is in a vibrational and rotational state having energy 0.50 ev when it absorbs a photon of frequency Hz. What is the energy of the final state of the molecule? a) 0.50eV b) 0.56eV c) 0.10eV d) 0.43eV e) 0.90eV 14. A radioactive source consists of atoms. It is observed that atoms decay per second. What is the half-life of the radioactive material? a) 1740 years b) 3200 years c) years d) 2200 years e) 1520 years 15. Which of the following statements about the Standard Model of particle physics is false? a) There are three known generations of leptons. b) Hadrons are bound states of quarks, or antiquarks. c) Bosons are the matter constituents. Fermions mediate the forces between particles. d) Strangeness is not conserved by the weak interaction. e) The weak force is short-ranged because of the large mass of the Z and W particles. 16. At room temperature (T = 300K), the occupation probability of an electron state in the valence band of Zn with kinetic energy 10% greater than the Fermi energy (E F = ev) is about: a) b) c) 0.94 d) 0.11 e) Two electrons with opposite spin are in an l = 0 orbital. A magnetic field of 1 T is present. What is the energy separation between the two electron levels? a) ev b) ev c) ev d) ev e) ev 18. K-mesons have an average proper lifetime τ. How fast must they move with respect to the earth so that an earth-based eperimenter will measure an average lifetime of 1.5 τ? a) 0.80c b) 0.40c c) 0.50c d) 0.75c e) 0.90c 19. The average person receives a dose of 102 m rem/year. If the average RBE of the radiation received is 1.5, how much energy, in Joules, is absorbed per year by a 70 kg person? a) 7.14 b) 4.76 c) d) e) Suppose the ratio of the density of free electrons in aluminum to to that in potassium is 3:1. If the Fermi energy in potassium is 1.3eV what is the Fermi energy in aluminum? a) 11.7 ev b) 2.7 ev c) 6.7 ev d) 3.9 ev e) 1.9 ev

13 21. A perfectly black body at C emits light of intensity I. The temperature of this body is now raised to C. The hotter black body now radiates light of intensity closest to: a) 2.6 I b) 2.0 I c) 4.0 I d) 8.0 I e) 1.4 I 22. In the energy level diagrams shown, the shaded region represents the occupied electron states beneath the Fermi energy. The white regions represent the empty electron states. Which answer best describes solids (I), (II), and (III)? a) (I) insulator, (II) metal, (III) semiconductor b) (I) semiconductor, (II) metal, (III) insulator c) (I) metal, (II) metal, (III) semiconductor d) (I) insulator, (II) metal, (III) metal e) (I) metal, (II) insulator, (III) semiconductor I II III conduction band valence band 23. The Ξ particle has the following properties: B = 1, S = 2, Q = 1. Which of the following is a possible quark combination for Ξ? a) c s s b) dss c) uds d) uss e) s s 24. If you were in a spaceship traveling at a constant speed close to the speed of light (with respect to earth), you might make the following observations: (I)That some of your physical dimensions were reduced. (II)That your mass was greatly increased. (III)That your pulse rate is a lot slower due to time dilation. Which of these observations could actually take place? a) (II) b) (III) c) (I) d) None of these effects would occur. e) More than one of these effects would occur. 25. The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. The inde of refraction of the liquid is: a) 1.25 b) 1.75 c) 1.67 d) 1.33 e) 1.50 "Hairy Eyeball" 4 ft E 3 ft

14 26. An object placed in front of a thin lens of focal length +5 cm produces an image 10 cm from the lens on the same side as the object. How far is the object from the lens? a) 10 cm b) 2.8 cm c) 5 cm d) 20 cm e) 3.3 cm 27. In the Bohr model of the hydrogen atom, which of the following transitions emits a photon with the longest wavelength? a) n=6 n=7 b) n=4 n=2 c) n=2 n=1 d) n=6 n=5 e) n=5 n=3 28. An atom with N electrons will be chemically inert if N=: a) 25 b) 20 c) 5 d) 10 e) A K α X-ray emitted from a sample has an energy of 4.08keV. What is the atomic number of the element producing this X-ray? a) 400 b) 20 c) 401 d) 21 e) A photon, an electron, and a baseball have the same momentum. Which has the largest de Broglie wavelength? a) electron b) baseball c) baseball and electron d) all have the same wavelength e) photon

15 Your name sticker with eam code Physics 228 Final MAY 12, 2009 Profs. Rabe and Coleman guess. At the end of the eam, hand in the answer sheet and the cover page. Retain this question paper for future reference and study. 8. When you are asked to open the eam, make sure that your copy contains all 30 questions. Raise your hand if this is not the case, and a proctor will help you. Also raise your hand during the eam if you have a question. 9. Please SIGN the cover sheet under your name sticker. A proctor will check your name sticker and your student ID sometime during the eam. Please have them ready. SIGNATURE: TURN OFF CELLPHONES NOW!!! 10. Good luck! Useful Information 1. The eam will last from 4:00 p.m. to 7:00 p.m. Use a #2 pencil to make entries on the answer sheet. Enter the following ID information now, before the eam starts. 2. 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. 3. Under STUDENT # enter your 9-digit Identification Number. 4. Enter 228 under COURSE, and your section number (see label above) under SEC. 5. Under CODE enter the eam code given above. 6. During the eam, you may use pencils, a calculator, and three handwritten inch sheets with formulas and notes, without attachments. 7. There are 30 multiple-choice questions on the eam. 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 c = speed of light = m/s q e = e = charge on an electron = Coulombs q p = +e = charge on a proton = Coulombs k e = N m 2 /C 2 N A = Avogadro s number = particles/mol k B = Boltzmann s constant = J/K Wien s Constant = m K σ = Stefan s Constant = W/(m 2 K 4 ) h = J-s h = ev-s (in units of electron volts-second) h = h = π Js hc = 1240 ev nm = 1240 MeV fm 1 ev = J 1 kev = 1000 ev µ B = Bohr Magneton = ev/t = J/T g-factor of electron = u = 1 atomic mass unit = MeV/c 2 m e = electron mass = kg m e c 2 = electron rest energy = MeV m p = proton mass = kg m p c 2 = proton rest energy = MeV m n c 2 = neutron rest energy = MeV m π ±c 2 = charged pion rest energy = MeV

16 m π 0c 2 = neutral pion rest energy = MeV M( 1 1H) = u 1rad = 0.01 J/Kg RBE = Relative Biological Effectiveness Temperature conversion: T (K) = T ( C) = 1.8 T ( F) Zeroes of temperature scale: K = 0 C =32 F 1 nm = 10 9 m 1 Å = m = 0.1 nm 1 µm = 10 6 m 1 mhz = 10 3 Hz 1 khz = Hz 1 MHz = Hz 1 GHz = Hz Some quantum numbers: Q/e B S u 2/3 1/3 0 d 1/3 1/3 0 s 1/3 1/3-1 L e L µ L τ e, ν e µ, ν µ τ, ν τ 0 0 1

17 1. In the diffraction pattern from a si slit diffraction grating, which phasor diagram represents the combination of electric fields from the si slits when the path length difference between light from neighboring slits is a third of a wavelength? a) I b) III c) V d) II e) IV (I) (IV) (II) (V) (III) 5. A K α X-ray emitted from a sample has an energy of 4.08keV. What is the atomic number of the element producing this X-ray? a) 400 b) 20 c) 21 d) 401 e) An atom with N electrons will be chemically inert if N=: a) 20 b) 10 c) 25 d) 15 e) 5 2. For a diatomic molecule, it is found that the rotational states l=0 and l=1 are separated in energy by ev. The moment of inertia of the molecule is: a) kg m 2 b) not enough information. c) kg m 2 d) kg m 2 e) kg m 2 3. When a nonrelativistic beam of electrons is focused down to a diameter, it is found that the electrons velocities perpendicular to the beam can be measured to a precision of v e. If a nonrelativistic beam of protons is focused to the same diameter, the protons perpendicular velocities can be determined to a precision of about v p = a) v e b) e) 2000 v e v e 2000 c) 10 v e d) 1 2 v e 4. An object placed in front of a thin lens of focal length +5 cm produces an image 10 cm from the lens on the same side as the object. How far is the object from the lens? a) 10 cm b) 2.8 cm c) 20 cm d) 5 cm e) 3.3 cm 7. The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. The inde of refraction of the liquid is: a) 1.25 b) 1.33 c) 1.75 d) 1.67 e) 1.50 "Hairy Eyeball" 8. The average person receives a dose of 102 m rem/year. If the average RBE of the radiation received is 1.5, how much energy, in Joules, is absorbed per year by a 70 kg person? a) b) c) d) 7.14 e) ft E 3 ft

18 9. In the energy level diagrams shown, the shaded region represents the occupied electron states beneath the Fermi energy. The white regions represent the empty electron states. Which answer best describes solids (I), (II), and (III)? a) (I) metal, (II) metal, (III) semiconductor b) (I) insulator, (II) metal, (III) semiconductor c) (I) semiconductor, (II) metal, (III) insulator d) (I) insulator, (II) metal, (III) metal e) (I) metal, (II) insulator, (III) semiconductor I II III conduction band valence band 10. In the Bohr model of the hydrogen atom, which of the following transitions emits a photon with the longest wavelength? a) n=2 n=1 b) n=6 n=7 c) n=5 n=3 d) n=6 n=5 e) n=4 n=2 12. Which of the following statements about the Standard Model of particle physics is false? a) There are three known generations of leptons. b) The weak force is short-ranged because of the large mass of the Z and W particles. c) Strangeness is not conserved by the weak interaction. d) Bosons are the matter constituents. Fermions mediate the forces between particles. e) Hadrons are bound states of quarks, or antiquarks. 13. A perfectly black body at C emits light of intensity I. The temperature of this body is now raised to C. The hotter black body now radiates light of intensity closest to: a) 4.0 I b) 2.0 I c) 2.6 I d) 8.0 I e) 1.4 I 14. In a Young s double-slit eperiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen that is 5 m from the slits is: a) 0.50 cm b) 0.25 cm c) none of the other answers d) 1.0 cm e) 0.10 cm 11. A diatomic molecule is in a vibrational and rotational state having energy 0.50 ev when it absorbs a photon of frequency Hz. What is the energy of the final state of the molecule? a) 0.90eV b) 0.10eV c) 0.43eV d) 0.50eV e) 0.56eV

19 15. If you were in a spaceship traveling at a constant speed close to the speed of light (with respect to earth), you might make the following observations: (I)That some of your physical dimensions were reduced. (II)That your mass was greatly increased. (III)That your pulse rate is a lot slower due to time dilation. Which of these observations could actually take place? a) (II) b) More than one of these effects would occur. c) (I) d) None of these effects would occur. e) (III) 16. The following masses are known: 1 0 n u 1 1 H u 7 3Li u. Given this information, the binding energy of 7 3Li, in MeV, is epected to be closest to: a) 48 b) 52 c) 43 d) 56 e) A particle in a bo of length L is in the n = 3 state. Which diagram in the figure best describes its probability distribution? a) V b) II c) III d) I e) IV (I) (III) (V) (II) (IV) 18. Suppose the ratio of the density of free electrons in aluminum to to that in potassium is 3:1. If the Fermi energy in potassium is 1.3eV what is the Fermi energy in aluminum? a) 11.7 ev b) 3.9 ev c) 6.7 ev d) 1.9 ev e) 2.7 ev 19. A radioactive source consists of atoms. It is observed that atoms decay per second. What is the half-life of the radioactive material? a) 1520 years b) years c) 2200 years d) 1740 years e) 3200 years

20 20. At room temperature (T = 300K), the occupation probability of an electron state in the valence band of Zn with kinetic energy 10% greater than the Fermi energy (E F = ev) is about: a) b) 0.11 c) d) 0.94 e) Two electrons with opposite spin are in an l = 0 orbital. A magnetic field of 1 T is present. What is the energy separation between the two electron levels? a) ev b) ev c) ev d) ev e) ev 22. A diffraction grating of total width 4 cm is illuminated with light of wavelength 577 nm. The second-order principal maimum is formed at an angle of What is the total number of lines (slits) in the grating? a) About b) About c) About 5000 d) About 8000 e) About The Ξ particle has the following properties: B = 1, S = 2, Q = 1. Which of the following is a possible quark combination for Ξ? a) uds b) s s c) uss d) dss e) c s s 24. K-mesons have an average proper lifetime τ. How fast must they move with respect to the earth so that an earth-based eperimenter will measure an average lifetime of 1.5 τ? a) 0.75c b) 0.80c c) 0.50c d) 0.90c e) 0.40c 25. The following rest energies are known: m e c 2 = electron rest energy = MeV m p c 2 m n c 2 m π ±c 2 m π 0c 2 = proton rest energy = MeV = neutron rest energy = MeV = charged pion rest energy = 139.6MeV = neutral pion rest energy = 135.0MeV A few months from now, the Large Hadron Collider (LHC) at CERN in Geneva will be operating. Suppose that a head-on collision between protons and antiprotons, each having a kinetic energy of 1700 MeV, produces the reaction p + p π + + π + H where H is the newly discovered Higgs particle. The Higgs is at rest and the π + and π depart in opposite directions, each with a kinetic energy of 110 MeV. What is the rest mass of the Higgs? a) 1420 MeV/c 2 b) 3180 MeV/c 2 c) 2388 MeV/c 2 d) 4777 MeV/c 2 e) 658 MeV/c 2

21 26. A concave mirror forms a real image which is twice the size of the object, but inverted. If the object is 20 cm from the mirror, the focal length of the mirror must be about: a) 10 cm b) 20 cm c) 27 cm d) 13 cm e) 40 cm 30. The threshold frequency for photoemission in silver is Hz. For what frequency will the photoelectric stopping potential be 1.36 V? a) Hz b) Hz c) Hz d) Hz e) Hz 27. A photon, an electron, and a baseball have the same momentum. Which has the largest de Broglie wavelength? a) all have the same wavelength b) baseball c) photon d) electron e) baseball and electron 28. Consider the decay sequence shown. Which of the following correctly identifies nucleus Y? 212 a) 84 Po 210 b) 82 Pb 208 c) 81 Tl 202 d) 80 Hg 209 e) 83 Bi 216 Po 84 α 212 Pb 82 β 212 Bi 83 β Y α α X β Pb 29. Protons are accelerated in a cyclotron with an internal field of 0.2 T. If beam eits at a radius of 2 m from the center of the cyclotron, what is the energy of the protons? a) 14 GeV b) 15.3 MeV c) 38.3 MeV d) 1.92 MeV e) 7.67 MeV

22 Your name sticker with eam code Physics 228 Final MAY 12, 2009 Profs. Rabe and Coleman guess. At the end of the eam, hand in the answer sheet and the cover page. Retain this question paper for future reference and study. 8. When you are asked to open the eam, make sure that your copy contains all 30 questions. Raise your hand if this is not the case, and a proctor will help you. Also raise your hand during the eam if you have a question. 9. Please SIGN the cover sheet under your name sticker. A proctor will check your name sticker and your student ID sometime during the eam. Please have them ready. SIGNATURE: TURN OFF CELLPHONES NOW!!! 10. Good luck! Useful Information 1. The eam will last from 4:00 p.m. to 7:00 p.m. Use a #2 pencil to make entries on the answer sheet. Enter the following ID information now, before the eam starts. 2. 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. 3. Under STUDENT # enter your 9-digit Identification Number. 4. Enter 228 under COURSE, and your section number (see label above) under SEC. 5. Under CODE enter the eam code given above. 6. During the eam, you may use pencils, a calculator, and three handwritten inch sheets with formulas and notes, without attachments. 7. There are 30 multiple-choice questions on the eam. 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 c = speed of light = m/s q e = e = charge on an electron = Coulombs q p = +e = charge on a proton = Coulombs k e = N m 2 /C 2 N A = Avogadro s number = particles/mol k B = Boltzmann s constant = J/K Wien s Constant = m K σ = Stefan s Constant = W/(m 2 K 4 ) h = J-s h = ev-s (in units of electron volts-second) h = h = π Js hc = 1240 ev nm = 1240 MeV fm 1 ev = J 1 kev = 1000 ev µ B = Bohr Magneton = ev/t = J/T g-factor of electron = u = 1 atomic mass unit = MeV/c 2 m e = electron mass = kg m e c 2 = electron rest energy = MeV m p = proton mass = kg m p c 2 = proton rest energy = MeV m n c 2 = neutron rest energy = MeV m π ±c 2 = charged pion rest energy = MeV

23 m π 0c 2 = neutral pion rest energy = MeV M( 1 1H) = u 1rad = 0.01 J/Kg RBE = Relative Biological Effectiveness Temperature conversion: T (K) = T ( C) = 1.8 T ( F) Zeroes of temperature scale: K = 0 C =32 F 1 nm = 10 9 m 1 Å = m = 0.1 nm 1 µm = 10 6 m 1 mhz = 10 3 Hz 1 khz = Hz 1 MHz = Hz 1 GHz = Hz Some quantum numbers: Q/e B S u 2/3 1/3 0 d 1/3 1/3 0 s 1/3 1/3-1 L e L µ L τ e, ν e µ, ν µ τ, ν τ 0 0 1

24 1. Which of the following statements about the Standard Model of particle physics is false? a) Strangeness is not conserved by the weak interaction. b) There are three known generations of leptons. c) The weak force is short-ranged because of the large mass of the Z and W particles. d) Bosons are the matter constituents. Fermions mediate the forces between particles. e) Hadrons are bound states of quarks, or antiquarks. 2. The Ξ particle has the following properties: B = 1, S = 2, Q = 1. Which of the following is a possible quark combination for Ξ? a) uss b) c s s c) uds d) dss e) s s 3. 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 5. Two electrons with opposite spin are in an l = 0 orbital. A magnetic field of 1 T is present. What is the energy separation between the two electron levels? a) ev b) ev c) ev d) ev e) ev 6. If you were in a spaceship traveling at a constant speed close to the speed of light (with respect to earth), you might make the following observations: (I)That some of your physical dimensions were reduced. (II)That your mass was greatly increased. (III)That your pulse rate is a lot slower due to time dilation. Which of these observations could actually take place? a) (III) b) More than one of these effects would occur. c) None of these effects would occur. d) (I) e) (II) 4. Protons are accelerated in a cyclotron with an internal field of 0.2 T. If beam eits at a radius of 2 m from the center of the cyclotron, what is the energy of the protons? a) 7.67 MeV b) 15.3 MeV c) 38.3 MeV d) 14 GeV e) 1.92 MeV

25 7. The following rest energies are known: m e c 2 = electron rest energy = MeV m p c 2 m n c 2 m π ±c 2 m π 0c 2 = proton rest energy = MeV = neutron rest energy = MeV = charged pion rest energy = 139.6MeV = neutral pion rest energy = 135.0MeV A few months from now, the Large Hadron Collider (LHC) at CERN in Geneva will be operating. Suppose that a head-on collision between protons and antiprotons, each having a kinetic energy of 1700 MeV, produces the reaction p + p π + + π + H where H is the newly discovered Higgs particle. The Higgs is at rest and the π + and π depart in opposite directions, each with a kinetic energy of 110 MeV. What is the rest mass of the Higgs? a) 658 MeV/c 2 b) 4777 MeV/c 2 c) 2388 MeV/c 2 d) 3180 MeV/c 2 e) 1420 MeV/c 2 9. The following masses are known: 1 0 n u 1 1H u 7 3 Li u. Given this information, the binding energy of 7 3Li, in MeV, is epected to be closest to: a) 52 b) 48 c) 43 d) 39 e) A particle in a bo of length L is in the n = 3 state. Which diagram in the figure best describes its probability distribution? (I) (III) (II) ψ( (IV) 8. An object placed in front of a thin lens of focal length +5 cm produces an image 10 cm from the lens on the same side as the object. How far is the object from the lens? a) 2.8 cm b) 10 cm c) 5 cm d) 20 cm e) 3.3 cm a) IV b) V c) III d) I e) II (V)

26 11. K-mesons have an average proper lifetime τ. How fast must they move with respect to the earth so that an earth-based eperimenter will measure an average lifetime of 1.5 τ? a) 0.40c b) 0.80c c) 0.50c d) 0.90c e) 0.75c 12. In the energy level diagrams shown, the shaded region represents the occupied electron states beneath the Fermi energy. The white regions represent the empty electron states. Which answer best describes solids (I), (II), and (III)? a) (I) metal, (II) metal, (III) semiconductor b) (I) insulator, (II) metal, (III) metal 13. A concave mirror forms a real image which is twice the size of the object, but inverted. If the object is 20 cm from the mirror, the focal length of the mirror must be about: a) 10 cm b) 13 cm c) 27 cm d) 20 cm e) 40 cm 14. A diffraction grating of total width 4 cm is illuminated with light of wavelength 577 nm. The second-order principal maimum is formed at an angle of What is the total number of lines (slits) in the grating? a) About 8000 b) About c) About d) About e) About 5000 c) (I) insulator, (II) metal, (III) semiconductor d) (I) semiconductor, (II) metal, (III) insulator e) (I) metal, (II) insulator, (III) semiconductor I II III conduction band valence band 15. Suppose the ratio of the density of free electrons in aluminum to to that in potassium is 3:1. If the Fermi energy in potassium is 1.3eV what is the Fermi energy in aluminum? a) 2.7 ev b) 3.9 ev c) 11.7 ev d) 6.7 ev e) 1.9 ev 16. For a diatomic molecule, it is found that the rotational states l=0 and l=1 are separated in energy by ev. The moment of inertia of the molecule is: a) kg m 2 b) kg m 2 c) kg m 2 d) not enough information. e) kg m 2

27 17. When a nonrelativistic beam of electrons is focused down to a diameter, it is found that the electrons velocities perpendicular to the beam can be measured to a precision of v e. If a nonrelativistic beam of protons is focused to the same diameter, the protons perpendicular velocities can be determined to a precision of about v p = 1 a) v v 2 e b) v e c) 10 v e d) e 2000 e) 2000 v e 18. A radioactive source consists of atoms. It is observed that atoms decay per second. What is the half-life of the radioactive material? a) years b) 3200 years c) 1520 years d) 1740 years e) 2200 years 19. In the Bohr model of the hydrogen atom, which of the following transitions emits a photon with the longest wavelength? a) n=4 n=2 b) n=2 n=1 c) n=5 n=3 d) n=6 n=7 e) n=6 n=5 20. A diatomic molecule is in a vibrational and rotational state having energy 0.50 ev when it absorbs a photon of frequency Hz. What is the energy of the final state of the molecule? a) 0.43eV b) 0.10eV c) 0.56eV d) 0.50eV e) 0.90eV 21. An atom with N electrons will be chemically inert if N=: a) 10 b) 25 c) 5 d) 20 e) In the diffraction pattern from a si slit diffraction grating, which phasor diagram represents the combination of electric fields from the si slits when the path length difference between light from neighboring slits is a third of a wavelength? a) V b) III c) II d) I e) IV (I) (IV) 23. The average person receives a dose of 102 m rem/year. If the average RBE of the radiation received is 1.5, how much energy, in Joules, is absorbed per year by a 70 kg person? a) 4.76 b) c) 7.14 d) e) A K α X-ray emitted from a sample has an energy of 4.08keV. What is the atomic number of the element producing this X-ray? a) 20 b) 401 c) 400 d) 21 e) 19 (II) (V) (III)

28 25. In a Young s double-slit eperiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen that is 5 m from the slits is: a) 0.10 cm b) 1.0 cm c) 0.50 cm d) none of the other answers e) 0.25 cm 28. At room temperature (T = 300K), the occupation probability of an electron state in the valence band of Zn with kinetic energy 10% greater than the Fermi energy (E F = ev) is about: a) b) 0.94 c) d) 0.11 e) Consider the decay sequence shown. Which of the following correctly identifies nucleus Y? 208 a) 81 Tl 202 b) 80 Hg 209 c) 83 Bi 212 d) 84 Po 210 e) 82 Pb 216 Po 84 α 212 Pb 82 β 212 Bi 83 β Y α α X β Pb 29. The threshold frequency for photoemission in silver is Hz. For what frequency will the photoelectric stopping potential be 1.36 V? a) Hz b) Hz c) Hz d) Hz e) Hz 27. The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. The inde of refraction of the liquid is: a) 1.75 b) 1.33 c) 1.50 d) 1.25 e) 1.67 "Hairy Eyeball" 4 ft E 3 ft 30. A perfectly black body at C emits light of intensity I. The temperature of this body is now raised to C. The hotter black body now radiates light of intensity closest to: a) 4.0 I b) 2.6 I c) 2.0 I d) 8.0 I e) 1.4 I