De Broglie Wavelength - Optics and Modern Physics - Solved Past Paper, Exams of Physics

Download De Broglie Wavelength - Optics and Modern Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! Physics 228 - Exam 2 ‘ 8 April 2010 Profs. Rabe and Coleman = Your name sticker with exam code => SIGNATURE Turn off and put away cell phones now! The exam will last from 9:40pm to 11:00pm. 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 (Last, First, M.L) 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. Enter 228 under COURSE, and your section number (see label above) under SEC. Under CODE enter the exam code given above. During the exam, you may use pencils, a calculator, and one handwritten 8.5 x 11 inch sheet with formulas and notes, with- out attachments. There are 16 multiple-choice questions on the exam. 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 guess. At the ened of the exam, hand in the answer sheet and the cover page. Retain this question paper for future reference and study. 10. 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. Please SIGN the cover sheet under your name sticker and have your student ID ready to show to the proctor during the exam. Useful information c= speed of light = 3.00 x 10° m/s de = —e = charge on an electron = —1.602 x 10-!® Coulombs % = +e = charge on a proton = +1.602 x 10-8 Coulombs Me = electron mass = 9.11 x 10-* kg mec” = electron rest energy = 0.511 MeV Mp = proton mass = 1.67 x 10-77 kg ™,C’ = proton rest energy = 938.27MeV m,C = neutron rest energy = 939.57 MeV kg = Bolizmann’s constant = 1.38 x 10-8 J/K Wien’s Constant = 2.898 x 10-°m- K o = Stefan’s Constant = 5.670 x 10-°W/(m?K*) Ask h = 6.626 x 10 Js h = 4,136 x 10-® eV-s (in units of electron volts-second) he = 1240 eV - nm = 1240 MeV - fm lnm =10%m 1A=10-°m=O0lnom 1 pm = 10-&m 1 mHz = 10° Hz 1 MHz = 10+* Hz 1 kHz = 10+? Hz 1 GHz = 10+? Hz A photon, an electron, and a baseball have the same momentum. Which has the largest de Broglie wavelength? _ a) photon c) electron d) baseball and electron e) baseball A particle is confined inside a cube of side length L, with one corner at the origin. The potential height of the walls of the cube is infinite. The normalized wave function of the particle, which is in the ground state, is 2\3/2 o(z,y,z)= (=) sin aa sinaysin mz, O<a2,y,2<b What is the maximum value of the probability distribution func- tion for an electron in this state? A pertectly black body at a temperature of 100°C emits light of intensity J that has strongest intensity at wavelength \. The temperature of the black body is now increased to 200°C. The hotter black body now emits light most strongly at a wavelength closest to a) O.5A b) d c) 2 d)} 13d yeh depends ony on momenhm . p “Aspens ovef Same momeatim—? Sane a. UY = (+ BY sin x sity sia‘ sintes somax value EEL is(2)73 = rf use Wien law Aml = 2.90 *10 mn K = 2.90x/02 mk = 2900 mk . 323. 473K _3BK_ FP X» A hotter 12. An electron is trapped in a one-dimensional infinite potential well of width 107!° m. What is the energy of the photon emitted when the electron makes a transition from the first excited state (n = 2) to the ground state (n = 1)? a) 0.062 eV b) 37-4 eV d) 127 eV e) 150eV 13. A distant star is receding from earth at a speed such that the 434-nm emission line of hydrogen is Doppler shifted to 650 nm. At what speed is the star receding? a) 0.667¢ b) 0.383¢ e) 0.995¢ 14. The wave character of electrons is best illustrated by which of the following? a) The fact that hot objects emit electromagnetic radiation. Gt diffraction pattern observed when a beam of electrons is scattered by a crystal. c) The scattering of alpha particles from gold foil. d). The ejection of electrons from a metal surface illuminated by light. e) The fact that a rainbow consists of a continuous spectrum of colors. c) 0.9999¢ d) 0.5¢ 15. (x) is the normalized wave function for a particle moving along the x axis. The probability that the particle is in the interval from z=atoz=b is given by: a) WO)? -|¥a)? 5) NG ¥(a) pada Swcoae 3 lvl) - Hla)? AE23 RR 2m LI ae) = 3. EXO els x6.66x10 “Ts 42 G11 510 Pkg - 107°? Per 7 A eu *c Cth "-(62) 2. 24 can ol gaadane 4 ca | 4 fee CS ansues aad gee whit one works diffrachion [5 a wave property b J Pde = ShHbol a 16. Avspaceship is moving at speed 0.70c to the right relative to earth. Standing at the rear of the ship, a woman fires a space gun, and the ‘ bullet goes forward inside the ship at a speed of 0.90c relative to Ve yitu > (0.4¢ + O-Fe x 0. 98 c the spaceship. What is the bullet’s speed as measured from earth? OS 1+ 0 q-0 F | say’ > __ c* O.7c. . a) 1,60c ce) 0.92c¢ d) 0.54e e) 0.20¢