Major Concepts of Physics II
Major Concepts of Physics II PHY 102
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This 23 page Class Notes was uploaded by Clement Bernier on Wednesday October 21, 2015. The Class Notes belongs to PHY 102 at Syracuse University taught by Liviu Movileanu in Fall. Since its upload, it has received 127 views. For similar materials see /class/225622/phy-102-syracuse-university in Physics 2 at Syracuse University.
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March 23 Profquot Liviju Movilleqnu http physics syr edu courses P HY 1 02 07Spr39i ng index h rmll IJ Room 21 1 IJdg 1 Major Concepts of Physics PHY 102 Lecture 16 2009 5ymcuse Universi39ry 1 Lecture objectives 1 The emission spectra Lecture Demo 2 Discovery of the atomic nucleus 3 The Bohr model of the hydrogen atom Radii and energy levels of the Bohr orbits Discuss conceptual examples O U lh AnnouncementsReading assignments Major Concepts of Physics PHY 102 Lecture 16 2009 yracuse University 2 Recall from the previous lecture The bundles of energy are called phofons39 They are particlelike The energy canno r be subdivided To a value less Than hf In rer39fer39ence exper39imen rs indica re Tha r ligh r is a wave Example The Young Two sli r experiment Major Concepts of Physics PHY 102 Lecture 16 2009 5yracuse Universify 3 Ii 17y of light Dualifyis The modern View of Night and olTs o of oi r39odjia rion Light is both a wave and o plor39l riclxe The experiment performed on lighf dictates which aspect is revealed Example The photoelectric effect reveals The particle Ilike photon aspect The Thomas Young experiment reveals interference wovelike aspect Major Concepts of Physics PHY 102 Lecture 16 2009 5ymcuse Universi l39y 4 A gas discharge l39ube 4 g iii sgf lL Gas ions Electrode 0 Neutral gas atoms 9 Electrons a Major Concepts of Physics PHY 102 Lecture 16 2009 5yracus University 5 emission spectra A 19th Century Mystery Now we are ready to tackle a big puzzle of 19th century science The Nature of light emitted by gases Observation The frequencies are discrete They are not continuous That is the light emitted by an excited gas has frequencies that take on separated precise values Each frequency is a characteristic eg fingerprint of the particular type of gas Do Demo Light from excited gas discharge tubes Contrast this with light emitted by a sold The frequencies are continuous Major Concepts of Physics PHY 102 Lecture 16 2009 5yracuse University 6 Ody Radiation Recall its basic facts Al frequencies of radiation are emitted but Varying intensities Contrast this with light from a gas All values of the frequency f bermeel the discrete allowed values are forbidden Major Concepts of Physics PHY 102 Lecture 16 2009 5ymcuse University 7 LighT from Gases WhaT happens in The Tube conTaining The gas gt There is a large elecTric poTenTiazl difference across The Tube ElecTrons rush across Tube and collide wiJTh gas aToms Energy is Transferred To The gas aToms They Then o eexcfe 1n This de exci l aTion process The aTomic energy is Turned inTo I g 1 Electrodenommma T mm amp r 99 M or Way E ectrode p 4 z 231353 1 llllllL 0 Neutral gas atorns 9 Gas ions 9 Electrons a Major Concepts of Physics PHY 102 LecTur39e 16 2009 Syracuse UniversiTy A neon sign is a discharge tube containing neon gas b Emissim spm m Fm i Qmig hydmg m indium mm mgmury eagyngmcme McGuerlH Cnmpzmes Inc Pevmwssmn rimmed im reproducuon or away Myumgcn m V 4 V 400 450 Sun 550 mm 650 7119 m 450 mu 50 mm 650 700 Nmn m i 4m 4w sun can rm 700 Nu m y uh V 4m 4m sun 550 mm 50 7w xmlcugm mun Majar Concepts of Physics PHY 102 Lecture 16 2009 Syracuse University 10 Setup for obtaining an absorption spectrum White light Gas source 7 Prism 7 r Collirnating r slits Absorption spectrum on screen Majur Concepts of Physics PHY 102 Lecture 16 ZODQOSyvacuse University 11 Emission spectrum of atomic hydrggen 1 1 1 R 2716 2 2 1 1 mi Wavelength a E E e E E s I m N In 0 o 1 v 1 N O V N 00 0quot 39 M D 00 v 1 W4 Lyman series Balmer series Paschen series I n n 12 Major Concepts af Physics PHY102 Laciura 16 2009 Syracuse Universiiy Thomson39s pl um pudding of The a rom Major Concepts of Physics PHY 102 Lecture 16 2009 5ymcuse University 13 Rufher for d sca i mring experimem Clpyngmi heMLGl HIHCDmpameanc Fen mymum auspmaummnmms 1 Radium ve mum mm M mm I i m l m vulxl ml mum M k 39 mum muirlc Major Concep39s cf Physics PHY 102 Lecture 16 ZOOD QSyracuse Univasi39y Bohr model of The hydrogen atom I a0 l I 3 2 1 Q I I 7 r3 Proton 0 Electron 0 Major Concepfs of Physics PHY102 Lecfur e 16 2009 Syracuse Universify 15 The hydrogen a rom Copyrighl 1 U quot Emitted photon l b Major Concepts of Physics PHY 102 Lecture 16 2009 5yracuse University 16 DavHum c The weme Carmemes Inc pmmn mum w muoamm Vimmy 1ny n w ur mm 5 HUM Hunk wrm E um i in mmquot m mm SM um wane mm imiva IWH m m nwlud mus y Mgior Concepfs of Physics PHY 102 Lecfure 16 200995yracuse University 17 Conceptual examples I Example 276 39 39 Finnl Sauces 1 0m wzluduug x m llle iurmml purl uf u hydmgcn plxuluu around 1 uV Tllumrum u hnul Maw m n 3 cmlsslun spccu um has Wu mellgm 128 um Whal am me Now we solve for me inl a mm H mum and nal 3 lax or me Lrilnsluo n ma msulls in mi crlcl39gy ox plmlon mmum I wavelengm hemg emmedz luluu energy lem 7 I39m cnergy level iwikljlcvr Stratcgy The energy my me lepm photon x39nllsl be me difference in Iwu energy level mun l ling m solxe an equation with Iwo unknowns the iniual and n vnluc ol nL we Cnl l use me energy level dinsmm lo nnrruw dawn um choice rm 5 The Lasrum phmon i cmlued when m elemen goes rmmu5lmx Solutlon no energy or me Phumn emmed h g all ev nm mm W Discussion For n phnmn in me llyllmgln ptmm A s m 39 Idenmylns me lower or me two energy Icvek L mpl ed l w 7m l I 39 r r n Dim Ion lnus be in me Puchcn senes The sluanst pllolon phelone in me Luna scnes lower energy level n 1 energy ln me Bnlmcr serlcs is haxe lurger energies um any of me photons in lhe ulmer 7 5 WP MW 9V scrim lowercncrgy level n I all erme photons in me Th Pme in m Lyman min hm W In E quotcry Balmer scncn haw In rcnclglcs Ihnn any 11 he Imam c Th l xenel and gt0 on r cr e e c hugmencrgy phomn in he Bracken series has mlcr 035 ev Only u Fahchun bunch e luulndc a PraLLiu Prubluu 276 Fi h Banner Line The llrsl four Balmcr line are cus y wavelpnglh arms rm 3 Imer Impquot u Isle Wlml is lllc MnJol Concepfs of Physics PHY 102 Lecture 16 2009 5yrncuss Universify 18 Conceptual examples Example 277 Thermal Excitation Absorbing or cmiuing piminn i run ll UNIV wily an mom can make u Ilansiiion bclwccn energy imis One of no oihcr Wnys Is tailed illcrmnlcxcimnon Ii hcur kmcn encr am if llyliirgclwo mums an quotI erguii meiasncmiiuionm which i ol39tlicmmakc mm i0n i Cxciicdsuualczw a Imnslniioimi kinetic energy a cr illc coliisicn Him a r x wage in Miunul kinetic c n h I 3 ii Wlml cucr yi anamm in gasallnom icmp mummu Kw bJExpluin h 39 mm Strmgy in swim my ialianai kincnc cnclgy or an ideal gas lo bc EC iii207 Tu fuciliunc cumparison ilh g we cunvcn hu avenge 39n T energy levels in hydm an energy l39he key N in CC C mlnslil wmll kinetic ciicrglrs oi iiic hydlogcn moms are huge Cllmlgll ih l an clnslic so u can exc e om or u moms 5 lt Solution and Discussion iii At T 300 K 1 H3720 x 138x iii l Jmen Kgtlt I V V60gtlt IO J v 0m av 1b Suppose mo alums mm in he giound slilic milidc To exam on of hem inm I Z the lmnsilion from he m n 7 m Th 260 limes hc memgc kineuc energy Al any ginii mm have lass VCI39y few have much mm man average The numbcl or uloms wiiii klllciic energies lziimlmrli opium he iivemge k ne L cnei gy is Namely small se Machilrkoiiuniuin disiribuiiun mum in Fig l m 39mmmmlminn mmr Major Concepts af Physics PHY 102 Lecture 16 ZOODOSyracuss University 19 Conceptual examples nc Fevmission ream ad in reprodunlion or mspi Copyrigm c The Mamaer Example 277 Conunued The iiny numbcr m alums cxcncd in mi wm39 quickly nn mm 2 7 an any given insiam a negligibly mall radian or he Absorpmn Spectrum onydmgm Awms 13 groundslm hydrogcn has nu black Imus m It visible pan ur the i x mum Ax high em me absorption specirum orammic hydrogen has four durkiiue n emib km i c w vcciigms as me four v In lines in he Balmsrsencml39ihccm on Spaclmmi Expli E E E Majar Concepts of Physics PHY 102 Lecture 16 ZOODOSyracuse University 20 r nzao n 1 2 3 2721 24 E1 218X10 ISJ l36eV 2723 E E 2 2724 71 Majar Concepts of Physics PHY 102 Lecture 16 2009 Syracuse Universiiy 21 Results of Bobquot Apply New ron39s 2quotCl Law and Coulomb39s Law To show The onyallowed radii r are r z r Here rn ner n r1 is called The Bohr radius The value of r1 is h24n2mke2 05259 1010 meters k is Coulomb39s Constant 1 47cso e is The electron charge Major Concepts of Physics PHY 102 Lecture 16 2009 5yracuse Universify 22 Announcements 1 Reading Chapter 27Th Section 276 Spectroscopy and early models of atom page 994997 Section 277 The Bohr model of the hydrogen atom atomic energy levels 9981002 Conceptual examples 276 277 2 This week39s workshop Workshop 9 3 HW 6 is due on this week s workshop Major Concepts of Physics PHY 102 Lecture 16 2009 yracuse University 23