Fermilab Tevatron - Optics and Modern Physics - Past Paper, Exams of Physics

Download Fermilab Tevatron - Optics and Modern Physics - Past Paper and more Exams Physics in PDF only on Docsity! Physics 228 - Second Common Hour Exam 30 March 2004 Profs. Shapiro and Conway ⇒ ⇐ Your name sticker with exam code Turn off and put away cell phones now! 1. THIS EXAM INCLUDES QUESTIONS WHICH REQUIRE A NUMERICAL ANSWER. The format on the machine- graded answer sheets re- quires that you express your answer is a very specific for- mat. Several examples are shown below: 5.30 should be entered as +5.30+00 437 should be entered as +4.37+02 0.62458 should be entered as +6.25−01 0 1 2 3 4 5 6 7 5 6 7 8 9 + − + − 8 6 7 8 9 E. 5 9 0 1 2 3 44 0 1 2 3 4 5 6 7 8 9 . . . . . . . . . .9 0 1 2 3 8 0 1 2 3 4 5 6 7 Form for numer- ical answers. 3 9 0 1 2 8 4 5 6 7 + − + − E- 1 .6 0 1 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 . . . . . . . . . . 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 The electron’s charge entered. −1.602176× 10−19 should be entered as −1.60−19. Note that all answers should be accurate to three signif- icant digits. A sample fragment of the mark-sense form is shown. Make sure you darken the circles! NOTE THAT MULTIPLE CHOICE QUESTIONS START WITH THE FIFTH QUESTION, BUT ITS NUMBER IS 16; ENTER THE ANSWERS ON THE MARK SENSE FORM ACCORDING TO THEIR PROBLEM NUMBERS, WHICH IN- CREASE HORIZONTALLY ACROSS THE FORM. 2. The exam will last from 8:00 pm to 9:20 pm Use a #2 pencil to make entries on the answer sheet. Enter the following ID information now, before the exam starts. 3. 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. 4. Under STUDENT # enter your 9-digit student ID. 5. Enter 228 under COURSE, and your section number (see label above) under SEC. 6. Under CODE enter the exam code given above. 7. During the exam, you may use pencils, a calculator, and one handwritten 8.5 x 11 inch sheet with formulas and notes, without attachments. 8. There are 16 questions on the exam. Several questions require you to enter a numerical answers as described above. Be sure to fill in the circles as well as writ- ing your answer in the boxes. The remainder are multiple-choice. For each multiple-choice question, mark only one answer on the answer sheet. There is no de- duction 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 the answer sheet and the cover page. Re- tain the rest for future reference and study. 9. When you are asked to open the exam, make sure that your copy contains all 16 questions. Raise your hand if this is not the case, and a proctor will help you. Also raise your hand during the exam if you have a question. 10. Please SIGN the cover sheet under your name sticker and have your student ID ready to show to the proctor during the exam. 1 Possibly Useful Information speed of light, c 3.00×108 m/s Planck’s constant, h 6.626×10−34 J·s hc 1240 eV-nm Rydberg constant RH 1.097×107 m−1 Bohr radius a0 0.0529 nm hydrogen ground state energy -13.6 eV elementary charge e 1.602×10−19 C electron mass 9.11×10−31 kg proton mass 1.673×10−27 kg neutron mass 1.675×10−27 kg visible light wavelengths approx. 400-700 nm 1 meter = 100 cm = 1000 mm = 106µm = 109 nm = 1012 pm 1 eV 1.602×10−19 J 1. The Fermilab Tevatron accelerates protons to a total en- ergy of 400.0 GeV. What is the relativistic factor γ for these particles? 2. The work function of silver is 4.73 eV. If light with wave- length 250.0 nm shines on the surface, what is the max- imum energy of the ejected photoelectrons, in eV? 3. An electron is trapped in a one-dimensional potential well with infinitely steep walls, and length 0.500 nm. Find the difference between the lowest two energy levels, in eV. 4. A helium ion in its unexcited state He+ has only one elec- tron in the 1s state. The wavelength of a photon which could excite it into the 3p state is (in nm) 16. Two twins decide to conduct an experiment. Twin A remains on the earth while twin B travels with constant speed υ = 0.6c to a star which is 4 light years away. How far does B think he has traveled to reach his destination? a) 2.4 light-years b) 3.2 light-years c) 5 light-years d) 5.3 light-years e) 6.7 light-years 17. The ‘proper time’ between two events is measured by clocks at rest in a reference frame in which the two events: a) occur at the same time. b) occur at the same spatial coordinates. c) are separated by the distance a light signal can travel during the time interval. d) occur with the maximum possible time interval. e) occur with the maximum possible spatial separa- tion. 18. A particle of mass M is at rest. It spontaneously breaks in two particles of equal mass, each moving at speed 0.6c in opposite directions. What is the mass m of either decay particle? a) 0.65M ≤ m < 0.85M b) 0.35M ≤ m < 0.45M c) 0.45M ≤ m < 0.65M d) m ≥ 0.85M e) m < 0.35M 2