ch2-10-sol - 9-“ 5’?” Physics 228 — Exam 2 ‘ 8...

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: 9-“ 5’?” Physics 228 — Exam 2 ‘ 8 April 2010 Profs. Babe 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, MI.) 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. ‘ 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 6 = speed of light = 3.00 x 108 m/s qe —e = charge on an electron = —1.602 x 10‘19 Coulombs qrp = +6 = charge on a proton = +1.602 x 10‘19 Coulombs me = electron mass = 9.11 x 10—31 kg mac2 2 electron rest energy = 0.511 MeV m,9 = proton mass = 1.67 x 10‘27 kg mpc2 = proton rest energy = 938.27MeV mncz = neutron rest energy = 939.57MeV k3 = Boltzmann’s constant = 1.38 x 10‘23 J / K Wien’s Constant = 2.898 X 10‘3m - K a = Stefan’s Constant = 5.670 x 10‘8W/(m2K4) h = _. h = glaze x 10-34 J—s h = 4.136 x 10—15 eV-s (in units of electron volts—second) he = 1240 eV - nm = 1240 MeV - fm 1 nm = 10—9 m 1.4 =10-10 m = 0.1 nm 1 pm = 10‘6m 1 mHZ = 10‘3 HZ 1 MHZ = 10+6 Hz 1 kHz = 10+3 HZ 1 GHZ = 10+9 HZ A photon, an electron, and a baseball have the same momentum. Which has the largest de Broglie wavelength? ‘ a) photon . F ' c) electron 1 ' SQ W MOW“? «WM "7 5V “"2 A v d) baseball and electron I 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 ‘ ¥ 2. 5 , 'L . 2.7T ylhz’ng ¢($,y,z) 2 (~) sinwxsinfiysinwz, O < 2:, y, z < L V g; ' 5’” fix 3"“ )l 3 L ‘ '7— L ch§5¥%/'§¥Z~):g What is the maximum value of the probability distribution "func— ‘- 51:? S 1. 5 Omax (/0 L ' [3" tion for an electron in this state? ' A perfectly black body at a temperature of 100°C emits light (/96 Wl‘ey‘ [aw KmTa x a m K of intensity I that has strongest intensity at wavelength A. The temperature of the black body is now increased to 200°C. The .5 p ‘3 5 hotter black body now emits light most strongly at a wavelengt A heifer c 2. X /0 '3 - closest to)‘ - A K .53 3'5 . > . . - A c) 2A d 1.3A An elementary article with rest mass m spontaneously decays . Par?! fig m . . . into two m With rest masses —. What are the kinetic energies A 3 of these particles? 93:14:12 a) E, me 32 T b) "1782,02 c) “L- e) %,0 If light incident on a metallic surface is doubled in intensity, the maximum kinetic energy of electrons produced by the photoelec- tric effect will change from K to: a) 4K b) 2K c) K /4 d ) K 2 e) K no change) As a spaceship heads directly to earth at a velocity of 0.8c, it sends a radio signal to earth. When those radio waves arrive on earth, their velocity relative to earth is: ' a c2 + 11%; , where ’UE is the velocity of the earth. c) _ \/ (.8c)2 + 01%; , where ’UE is the velocity of the earth. d) 1.8 c. s a - e) 0.8 c. Accelerating voltages in cathode—ray-tube (CRT) TV’s are about 24.0 k-Vr What is the shortest wavelength of the X~rays that are produced when the accelerated electrons hit the screen? a) 52nm b) 5.6 x101st ci 0.008nm e) 7.8nm . K K a <""‘° H Me?- = filCZ‘l’ K)"2 K: MC?" M 6; ouywhj eke/Mas MAME on? on ’F o incommj 0431M“, mt I. 7A2 SPeed 6F @144" f5 ‘0 m w “famq ##3' f 1 energy cl, mmmlvxg ~9le iS 24%105 Cl/ ajsume W mnWUfM (( my f» 56nch Pliers”! E=hc >\= he 2 (mo €V'nm s 0.05M» 7: “1;— 24000 €\/ 10. V 11. A meter stick moves in the laboratory along the direction of its ‘ _ length With a speed of 1.2 x 108 m/sec. Its length, as seen by an . observer at rest in the laboratory, is: a) 1.09 m b) 1.19 m d) 0.84 m e) 1.00 m A hydrogen atom undergoes a transition from the n '=' 6 to the n == 2 state by emitting a photon. According to the Behr model of the atom, if the angular momentum'is conserved,’ What is the angular momentum of the photon that is emitted? a) 371 b 0n c) 4 d) 1% e) 271 The uncertainty in position of an electron in a certain state is 5 X 10‘10 m. The uncertainty in its momentum (in kgOm/s) must be: a) less than 10‘23 b) greater than 10“20 c) less than 10‘25 fl ; eater than 10‘25 . e) greater than 10“23 Consider an electron With the free-particle wavefunction 2M1", t) = Aexp[i(kx — wt)]. Which of the following is false? a) the energy of the electron is fiw. b) ‘A can be chosen to be a pure imaginary number. 0 "Mac, t) is not a stationar state. 4 d the momentum of the electrOn is his . e) the probability distribution function is independent of as. Wt =A*A 12. 13. 14. 15. An electron is trapped in a one-dimensional infinite potential well of Width 10‘10 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 z 1)? a) 0.062 eV b) 37.4 eV ' ' d) 127 eV e) 150 eV A distant star is receding from earth at a speed such that the -V - ' 434—nm emission line of hydrogen is Doppler shifted to 650 nm. At what Speed is the star receding? a) 0.6670 b) 0.3830 e) 0.9950 c) 0.9999c d) 0.5c r The Wave character of electrOns is best illustrated by which of the following? a The fact that hot objects emit electromagnetic radiation. @The 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. ' rpm) is the normalized wave function. for a particle moving along the cc axis. The probability that the particle is in the interval from wzatomzbisgivenby: do wow—wow m ww—wm Know C , e W@—¢@P Ewmwm L Q =IN%» . +2. Eng: fill ' 2W?» 2. 4923 la ’2. W2 .Zm L2. _‘ -3 $139on lSet/z: *4.626X/0 93—5 7.1/ m2 “Wk-5 - Io‘z°m 2.. _ -—u' :C+u;\ Jawléwfie/l 2:67 ° '_ difi‘m 0507‘ [5' a wave b fZLde .— _a §§a5;22% . . c+u i" - 6’“ 43‘} b jlvsflta 0v 16. A spaceship is moving at speed 0.700 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 0,900 relative to the spaceship. What is the bullet’s speed as measured from earth? 0.7c.< ...
View Full Document

This note was uploaded on 02/27/2012 for the course PHYSICS 750:228 taught by Professor Karinrabe during the Spring '10 term at Rutgers.

Page1 / 6

ch2-10-sol - 9-“ 5’?” Physics 228 — Exam 2 ‘ 8...

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