Dual Nature of Matter and Radiation

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Evan Newman
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1 Higr Ordr Tinking Skill Qustions Dual Natur of Mattr and Radiation 1. Two bas on of rd ligt and otr of blu ligt of t sa intnsity ar incidnt on a tallic surfac to it otolctrons wic on of t two bas its lctrons of gratr kintic nrgy? c W 0 0 c 1 w w T oton of blu ligt its lctrons of gratr kintic nrgy tan tat of rd ligt, bcos largr wavlngt of rd tan blu. 2. Ultraviolt ligt is incidnt on two otosnsitiv atrials aving work functions W1 and W2 (W1> W2). In wic cas will t kintic nrgy of t ittd lctron gratr? Wy? K.E. for tal of Work function W2will b gratr. As Ek = - W. sall as work function gratr K.E. 3. Ultraviolt radiations of dfrnt frquncis 1 and 2 ar incidnt on two oto snsitiv, atrials aving work functions W1 and W2 (W1> W2) rsctivly. T kintic nrgy of t ittd oto lctrons is sa in bot t cass. Wic on of t two rlations will b of t igr frquncy? According to Einstin's otolctric quation, Ek = - w As Ek is sa, 1 - w1 = 1 - w2 w 1 w2

2 Or 1-2 =, As w1> w2, 1 >2 So frquncy of radiation 1 is igr. 4. An lctron, an ala articl and a roton av t sa kintic nrgy, wic on of ts articls as (i) t sortst and (ii) t largst, d- Brogli wavlngt? 1 2E k For sa kintic nrgy (i) Out of givn articl, t ass of ala articl is axiu so d Brogli wavlngt associatd wit ala articl is sortst. (ii) As ass of lctron is last, so lctron as largst d Brogli wavlngt. 5. An lctron and a roton av t sa d Brogli wav lngt associatd wit t. How ar tir kintic nrgis rlatd to ac otr? Givn = 2E k 2 E 2 F E E 1840 i.. K.E. of lctron = 1840 K.E. of roton. 6. An lctron and ala articl av t sa kintic nrgy. How is tir d Brogli wavlngt associatd?

3 7. d-brogli wavlngt associatd wit an lctron acclratd troug a otntial diffrnc V is. Wat will b t d-brogli wavlngt wn t acclrating.d. is incrasd to 4V? 1, v 1 V V An articl and a roton ar acclratd fro stat of rst troug t sa otntial diffrnc V. Find t ratio of d-brogli wavlngt associatd wit t? 2qv 2 4 2v, 2 4 v 1 8 : 1: Two tals and av work function 2 v and 4V rsctivly wic tal will it lctrons wn irradiats wit ligt of wavlngt 400 n and wy? Ans: -34 c Tis is gratr tan work function of, but lss tan work function of so tal will it lctrons. 10. In a lot of otolctric currnt vrsus anod otntial, How dos. (i) t saturation currnt vary wit anod otntial for incidnt radiations of diffrnt frquncis but sa intnsity. (ii) t stoing otntial vary for incidnt radiations of diffrnt intnsitis but sa frquncy? 8

4 (iii) Potolctric currnt vary for diffrnt intnsitis bid sa frquncy of incidnt radiations? Justify your answr in ac cas. Ans. (i) In otolctric affct t salvation currnt dos not vry wit anod otntial wit incidnt radiation of diffrnt frquncis. T rason in tat satiations currnt dnds only on intnsity of incidnt radiation bcaus a singl oton can jct a singl lctron, owvr larg t frquncy of radiation ay b. (ii) obviously stoing otntial is indndnt of intnsity rovidd frquncy rains uncangd, tat is stoing otntial dos not vary wit intnsity of incidnt radiations. (iii) Potolctric currnt incrass wit incras of intnsity bcaus incras in intnsity of radiation ans incras in ubr of incidnt otons As on oton jcts on lctron, incras intnsity caus incras in otolctric currnt. 11. Sow tat Bor's scond ostulat 't lctron rvolvs around t nuclus only in crtain fixd orbit witout radiating nrgy can b xlaind on t basis of do. Brogli yotsis of wav natur of lctron. Ans: T d Brogli wavlngt v Now for lctron in orbit 2r n (for nt oribit) n 2r v n or vr 2 Tis is Bor's scond ostulat. As colt d-brogli wavlngt ay b in crtain fixd orbits. So non-radiating lctron can b only in crtain fixd orbit.

5 12. Rd ligt owvr brigt it is, can roduc ission of lctrons fro a clan zinc surfac, but vn wak ultraviolt radiation can do so, wy? Ans. T nrgy of oton of U.V. ligt is gratr tan t work function of Zinc, so ultraviolt can it oto lctrons vn intnsity is wak. Wil t nrgy of oton of rd colour oton is lss tan work function of zinc. So t otolctric ission is in dndnt of in8. FOR PRACTICE 1. For wat uros, faous Davison Grrxrint wit lctrons rford? 2. If t otntial diffrnc usd to acclrat lctron is trild, by wat factor dos d Brogli wavlngt of lctrons ba cang. 3. Two tals and wn illuinatd wit aroriat radiations it otolctrons. T work function of is igr tan tat. Wic tal as igr valv of trsold frquncy and wy? 4. For a otosnsitiv surfac, trsold wavlngt is 0. Dos otoission if t wavlngt radiation is (i) or tan 0 and (ii) lss tan 0? Justify your answr. 5. How will t otolctric currnt cang on dcrasing t wavlngt of incidnt radiation for a givn oto snsitiv atrial? 6. Wat is t d Brogli wavlngt (in A 0 ) associatd wit an lctron acclratd troug otntial diffrnc of 100 volt. 7. An lctron and a roton av t sa kintic nrgy, wic on of t two as t largr wavlngt and wy?

6 8. T wav lngt of lctroagntic radiation is doubld. How will t nrgy of a oton cang?. 9. Wn is t stoing otntial alid to a oto cll is t axiu, (Kintic nrgy of oto lctron to b 5 v)? 10. Two tal A and B av work function 2 v and 4 v rsctivly wic tal as a lowr trsold wavlngt for otolctric ffct? 11. Work function of sodiu is 2.3 V. Dos sodiu sow oto lctric ission for ligt of wavlngt 6800Ǻ 12. A roton and a dutron av t sa vlocity, wat is t ratio of tir d Brogli wavlngts?

Physics 43 HW #9 Chapter 40 Key

Physics 43 HW #9 Chapter 40 Key Pysics 43 HW #9 Captr 4 Ky Captr 4 1 Aftr many ours of dilignt rsarc, you obtain t following data on t potolctric ffct for a crtain matrial: Wavlngt of Ligt (nm) Stopping Potntial (V) 36 3 4 14 31 a) Plot