3. What is the threshold frequency of a metal that has a work function of 3.3volts?

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1 Sale Questons: Cater 7 Potons 1. Calculate te energy o a oton o red lgt (5 ), volet lgt (7 ) Fnd te K o te ost energetc electron ejected ro a etal by a radaton o requency 7 te work uncton o te etal s V. V 1.6 K(ax) at s te tresold requency o a etal tat as a work uncton o 3.3volts? 3.3V ll lgt o requency 4 eject electrons ro a etal wose work uncton s 5V? xlan your answer. 5V s less tan so no eson 5. Lgt o a requency above te tresold requency alls on a gven etal. As te ntensty o te lgt s ncreased: wat aens to te nuber o otoelectrons ejected ro te etal? More electrons are etted snce ore otons are allng on te etal. wat eect does t ave on te axu knetc energy o te electrons? None. Only a ore coous eson o electrons.

2 6. xlan wat s eant by te work uncton o a etal. y would you exect ts to der or derent etals? Te ork Functon s te nu energy necessary to be absorbed (by te ost energetc electron) to allow a otoelectron to be etted. 7. Coer as a tresold requency o 9. at s te nu energy requred to release a otoelectron? Lgt o wavelengt 3-7 alls on a coer catode. Is te requency o te lgt sucent to release otoelectrons? I so, wat wll be te axu knetc energy o te released electrons? 34 c son snce > K(ax) Te energy needed to release an electron ro sodu etal s.3ev. at s te energy n?.3ev 3.6 Calculate te tresold requency o sodu and ence deterne weter or not orange lgt o wavelengt wll be able to release electrons ro te sodu surace c en lgt o wavelengt 4-7 alls onto te etallc surace o a otoelectrc cell, te negatve otental requred to sto te current s.v. at s te work uncton o te etal? c

3 . Te stong voltage o a otoelectrc cell s 1.volts wen lgt o wavelengt alls on te catode surace. V S 1.Volts c at s te axu knetc energy o te etted electrons? ax 1.6 at s te work uncton o te catode?.1 at s te tresold requency o te etal o te catode? 11. Te work uncton o a etal s at s te nu requency wc wll roduce otoelectrc eson? 9.6 Calculate te axu energy o te otoelectrons etted te wavelengt o te ncdent lgt s.4-7. ax c at would be te otental necessary to sto te otoelectrc current wt te ncdent lgt o? V e. S V S 1.43volts

4 1. In a otoelectrc exerent usng a clean sodu surace, te axu energy o te etted otons was easured or a nuber o derent ncdent requences, wt te ollowng results. Frequency ( ) nergy (ev) Plot te gra o tese results and ence nd: Planck s constant te tresold requency o sodu. nergy(ax) Poto-electrc ect y x F r e q u e n c y ( e r t z ) 13. A otosenstve surace C s llunated wt onocroatc lgt o successvely derent wavelengts. Te dagra below llustrates tat otental derences ave to be aled between C and A to revent electrons released by te lgt ro crossng to te collector A and regsterng as a current on te aeter G. Te values o otental derence wc just sto electrons reacng A are as ollows: C A A avelengt ( -7 ) Potental Derence (V)

5 Plot a sutable gra and ence deterne: te tresold requency, te work uncton o te surace A, te value ts exerent nds or Planck s constant, te axu knetc energy (n ) wt wc electrons are ejected ro te surace by te lgt o wavelengt avelengt(etres) Frequency(ertz) nergy() Stong Voltage (volts) Stong Voltage y 7x - 3 nergyax() Frequency(ertz). A otental derence o V s aled across an x-ray tube. Calculate te nu wavelengt or te x-rays roduced. nergy avalable Ve 1.6 I all ts knetc energy s converted nto a oton c etres n 15. at otental derence ust be aled across an x-ray tube to roduce x-rays wt a nu wavelengt o 1? 34 c 3 V V 1.4 volts

6 16. lectrons are accelerated n an x-ray tube by a otental derence o 5V. at energy do tey ave on reacng te target? nergy Ve at s te sortest wavelengt o te contnuous x-ray sectru roduced? c etres I te electrons are stoed n a dstance o -5, calculate ter average acceleraton wle beng stoed. nergy v v v v v K as ( 1.33 ) a.79 a An X-ray tube as a otental derence o 33volts between te laent and te anode. at s te gest requency o te X-rays etted by te tube? Ve I all ts energy converted to a oton ten ax 5. ax 1. An electron s accelerated across a otental derence o V n an X-ray tube. I 6% o te energy o te electron s converted to eat, nd te eat roduced 6% o energy s converted to eat Ve te requency o te X-ray oton etted. 19 ax

7 19. at s te oentu o a oton o x-radaton o wavelengt 1? 11-3 secn. Calculate te oentu and energy o a oton o yellow lgt o wavelengt 6. -7? secn c Calculate te debrogle wavelengt o: a kg car ovng at. -3 etres an electron accelerated troug a otental derence o V. 1.6 v K etres. At wat seed does an electron ave a debrogle wavelengt o. -? v v A bullet o ass.kg s red wt a velocty o. at s ts debrogle wavelengt? etres ll te wave nature o ts ass be observable? xlan. No. Far too sall to be observed.

8 4. An electron as a debrogle wavelengt o 5 -. at s ts oentu? secn at s ts velocty? v v ll electrons o ts velocty ave arecable dracton eects wen scattered ro a crystal? Yes. Snce s slar n sze to te dstance between ato n a crystal, t wll be dracted. (d) Troug wat otental derence ust te electrons travel to aceve ts velocty? at tye o acne can rovde ts otental derence? c 3 5 V e.4 3 volts 5. An electron as an energy o 6eV. Fnd: ts velocty 6eV 9.6 v K te electron s oentu v secn 1.45 ts wavelengt etres