solutionsexam2

solutionsexam2 - SOLUTIONS Physics 273- Exam H Wednesday,...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: SOLUTIONS Physics 273- Exam H Wednesday, November 2, 2011 Prof. Mohan Kalelkar Your name sticker and exam code . The exam will last from 1:45pm to 2:50pm. Use a # 2 pencil to make entries on the answer sheet. Enter the following id information now, before the exam starts. ‘ . In the section labelled NAME, 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. . Under STUDENT # enter your 9—digit Student ID Number. Under COURSE enter 273. Under CODE enter the exam code given above. . During the exam, you may use pencils, a calculator, and ONE 8%” x 11” sheet of paper with formulas and notes. . There are 16 multiple—choice questiOns on the exam. For each ques~ tion, mark only one answer on the answer sheet. There is no subtrac- tion 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 end of the exam, hand in only the answer sheet. Retain this question paper for future reference and study. . Useful numerical constants are given on the next page. Before starting the exam, make sure that your copy contains the page of constants and all 16 questions. Bring your exam to the proctor if this is not the case. Elementary charge e = 1.6 X 10‘19 C 1 electron volt (eV) 2 1.6 x 10‘19 J Speed of light 0 = 3 X 108 m/s Planck’s constant h = 6.63 X 10‘34 J v s = 1240 nm u eV/c h = h/27r Compton wavelength of electron h/mc = 0.0024 nm Ground—state energy of hydrogen = —-13.6' eV Rydberg constant R = 0.0109678 nm‘l Avogadro’s number = 6.02 X 1023 molecules/mole Electron mass = 9.11 X 10‘31 kg = 0.511 .MeV/c2 Proton mass = 1.673 X 10—27 kg = 938.3 Il/[eV/c2 Neutron mass = 1.675 X 10“27 kg = 939.6 MeV/c2 Atomic mass unit 1 u = 931.5 M eV/ 02 Fine structure constant oz 2 1 / 137 Bohr magneton ,LLB = 5.79 X 10'5 eV/T Energy ordering of subshells: ' 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p Values of l for subshells: spdfgh 012345 Powers of ten: femto(f) pico(p) nano(n) micro(,u) milli m 10—15 10‘12 10—9 10—6 10—3 ( ) centi(c) kilo(k) Mega(M) Giga(G) Tera(T) 10—2 10+3 10+6 10+9 10+12 1. An electron has a total energy of 0.7 M eV. What is its DeBroglie wave- length? l m l ,5. v» 2 «we a 6 my *9 a) About 0.0026 mm P a 2“ LEN/1M9 z ' #72:», b) About 0.0010 nm a J. L” (0.701% 0) About 0.0066 mm c ¢V d) About 0.0018 nm /fi 1240 7m - *6" e) About 0.0014 nm A 5-”— .75/ r . 457gx/oé 1%! 2. A particle has a wave function given by ¢(CE) = 140:2 in the region 0 < a: < L, ' and zero elsewhere. What is the value of A? L- a) 1/.L2 N ‘ o , $4145”an :7 ,b) /3/L3 L- 9 2 L 0% élaffl‘kW“”“ I r“? d) V5/L5 .. E 5‘ e) None of the other answers I? (q ‘A /1“ ;: . Vflzémm' 3. A particle has a wave function given by $06) = M5751— sin if in the region 0 < a: < L, and zero elsewhere. What is the prObability that the particle lies between a: = 0 and a: = L/3? L/B L/3 ' . In. M TI'X a)1/\/§ Ffifllflseyo’ogg 37:51 “A b) 1/3 0 'D C) 1/9 L/‘3 . d) 9 7r 5., 231 gmuiwpzfl .9334 33;”‘71-[C957LJ0 zfzai‘ A4, 4. Which of the following statements are true? 0 I: A proton confined within a nucleus cannot be perfectly at rest. .0 II: If the wave function of a particle is zero at some point, the particle has zero probability of being found at that point. ' 0 III: Theposition and momentum of a particle cannot be simultane~ ously measured to perfect accuracy. a) I and III are true; II is false "v? b) All three statements are true 0) I and II are true; III is false d) III is true; I and II are false e) II and III are true; I is false ,9 grmawwwww 5% 5. An electron (mass = 0.511 MeV/cg) and a proton (mass = 938 MeV/c2) have the same DeBroglie wavelength. Which of the following statements is true? a) The electron’s momentum is greater than that of the proton b) The proton’s momentum is greater than that of the electron c) The electron’s total energy equals that of the proton. d) The electron’s total energy is greater than that of the proton ".5- e) None of the other statements are true 6. A particle in an infinite square wellhas an energy of 8 eV in the FIRST - EXCITED state. What are its energies in the GROUND state and the SECOND EXCITED state respectively?2 2% 2 V y a) 4eVandl2eV Ea “7 4W1 52‘38' 2 b) 4eVand36€V “ 2W“ 2 . I w 2 V .~>c) ZeVand18eV AD. 5‘ 7; {gag} -:=- 67:62 z- .e . d) x/EeVandlfieV e) x/EeVand64eV # 32 "E ,7; 24V 53 '- figi 51 "‘ 4(2) / ‘ 7. Which of the following are possible sets of quantum numbers for an electron in an atom? oI:n=4, l=2, mlz—Z, msz—l/Z a) I is possible; II and III are not b) None of the three are possible -———> c) I and III are possible; II is not d) All three are possible e) III is possible; I and II are not 8. An electron is in a state of zero orbital angular momentum. What are the possible angles that its spin angular momentum vector can make with the z-axis, which could be the direction of an external magnetic field? -—>a) 55°and125° gaWJfi: .ngfi’. "mi .. b) 45° and 135° c) 60° and 120° 5- .. jL$ o o a 2, d) 0 and180 I e) 90°only Cpga’; 2;: iii 1 i J, , “'2‘ 52; 559mm 235°, 9. A certain subshell can have a maximum of 10 electrons. Which of the following could that subshell be? . ,a - ' I 5% a) 3s MAXIMUM W W 2(2’Z+) b , , n” . (32?; aka/wt AW- d) 4f ' . . .__> e) None of the other answers 10. Consider a complex atom in a state in which the spin quantum number is 2, and the orbital angular momentum quantum number is 3. What are all the possible values of the total angular momentum quantum number? ))374)5 :3 “‘5 ‘,,, 9:3 loin T IL [3 J C ) c) Sonly :' I3“2’) .0, (3+2) d) 1and5 e) 1,3,5 '5 1,9:324’35 11. A neutral atom of silicon has 14 electrons. Which of the following is the electron configuration for the ground state of silicon? a) 1s22s22p62d4 w“? b) 1s22s2.‘2p6f:.’s23p2 c) 1s22s23s23p63cl2 d) 1s21p62s22p4 e) None of the other answers 12. In the real universe, the first two inert gases occur at atomic numbers Z of 2 and 10. At what values of Z will the first two inert gases occur in a hypothetical universe in which the spin quantum number of the electron is 32’tdf12? - _ /1nsea 0/ Ac”; .9 MAT...“ ~%}~é~;é‘i g: a) 2and10 b) 4and16 ‘ Fm We: 97; WA ' 4 .9) 4 IlClZO .. I . .. ' g) 62nd30 4'“ WWW IA” ) e None of the other answers W W W : 132 JAE 24f“ 2/9 , W$4)/€93) 4*:- l, #3; 4-. 3/2.; Lag-5‘“ 2L5wsfl 13. An atom is in a 43F4 state. For this state, what is the angle between the orbital and spin angular mOmenturn vectors WITHIN the triangle for vector ddii n f h n 111 m ' ? . a to O t esea gj7g'vS/I31:n:;/fl+7)+4@+l)”2 £(f+f)mc72€fl‘ a) About 35° 3% 2521:2283 45st mm. r(2)—~2;/2’2’/‘2‘m59 V all; ==> c0594 «m 7:» M W - 14. In the preceding problem, suppose the atom in the 43174 state is placed in a weak magnetic field B. What will be the spacing in energy between adjacent magnetic substates? . ' AE My WEB W 4’3"- a) 0.67%]; . ab) 1,25,11,38 ___ Zia/'44) +A(A+z) "j (2 +1) c) 1.50/iBB g“]"}’ Q.(-+O d) 2.00MB 0’1 é e) 133MB __ 4(9)+ MEI-AM) : /, 25‘ " 1+ 20% 15. The outer electrons in Silicon have the configuration 3323192. For Aluminum it’s 3323101, and for Indium it’s 5325101. If Silicon is doped with Aluminum or Indium, What kinds of semiconductors (if any) are formed? £4 M W a) n~type for Aluminum, ip~type for Indium D M b) p~type for Aluminum, n~type for Indium J”: M W: a c) p~type for both d) p~type for Aluminum, neither for Indium because the outer electrons are not in the n = 3 shell M M a, e) n—type for both 4 a M a , :effie 16. A hydrogen atom undergoes a transition from a state of quantum number n to‘a state of quantum number (null). The Bohr radius of the atom drops by a factor of nine as a result of the transition. What is the value of n? ’ 1 a) 13 , 7i:- 7120v0 219: (n-4)2a,a “”‘? d) 6 f O ‘ e) None of the other answers g 5 )77',’ 72n+ "II/y“ " w“) W Wimg3flg~ - m73W/‘fi MgrfWW/fi'n”ép‘ ...
View Full Document

Page1 / 6

solutionsexam2 - SOLUTIONS Physics 273- Exam H Wednesday,...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online