Lect26 - Physics 212 Le cture26: Le s nse Le Le 50 40 30 20...

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Unformatted text preview: Physics 212 Le cture26: Le s nse Le Le 50 40 30 20 10 0 Confused Avg = 3.0 Confident Physics 212 Le cture26, S 1 lide Music Who is the Artist? A) B) C) D) E) Pete Fountain Dr. Michael White Al Hirt George Lewis Dr. John BB Why?? Why?? I he “Horn Man Blue on theradio com in this m ard s” ing orning! Maste of traditional Ne Orle jazz !! r w ans The eof thewe k: C m e lassic Jazz C oltraneand Dr. Michae White l Physics 212 Le cture26, S 2 lide Physics 212 Le cture26: Le s nse Le Le 50 40 30 20 10 0 Confused Avg = 3.0 Confident Physics 212 Le cture26, S 3 lide Re fraction S ll’s Law ne n1sin(θ 1) = n2sin(θ 2) θ1 n1 n2 θ2 That’s all of thephysics – That’s e rything e is just ge e ve lse om try! Physics 212 Le cture26, S 4 lide Obje Location ct • Light rays fromsun bounceoff obje and go in all dire ct ctions om ye – S ehits your e s Weknow obje location by ct’s whe rays com from re e . Wewill discuss e s in le ye cture28… Physics 212 Le cture26, S 5 lide Wave fromobje arefocuse by le s ct d ns Physics 212 Le cture26, S 6 lide Ray Tracing can beuse to de rm I m d te ine age Physics 212 Le cture26, S 7 lide Two Diffe nt Type of Le s re s nse Physics 212 Le cture26, S 8 lide C rging Le Conside thecasewhe theshapeof thele is such that light rays onve ns: r re ns paralle to theaxis of them l irror areall “focuse to a com on spot a distancef be d” m hind be thele t he ns: f f Physics 212 Le cture26, S 9 lide Re for finding im : cipe age 1) Draw ray paralle to axis l 2) Draw ray through ce r nte re fracte ray goe through focus d s re fracte ray is sym e d m tric object f image You now know theposition of thesam point on theim e age Physics 212 Le cture26, S 10 lide 10 S> 2f im is: age re al inve d rte sm r alle 111 += S S′ f S′ M =− S obje ct f im age f S S ’ Physics 212 Le cture26, S 11 lide 11 S= 2f im is: age re al inve d rte sam size e 111 += S S′ f S′ M =− S obje ct f im age f S S ’ Physics 212 Le cture26, S 12 lide 12 2f > S> f im is: age re al inve d rte bigge r 111 += S S′ f S′ M =− S obje ct f im age f S S ’ Physics 212 Le cture26, S 13 lide 13 S= f im is: age at infinity… 111 += S S′ f S′ M =− S obje ct f f S Physics 212 Le cture26, S 14 lide 14 0 < S< f im is: age virtual upright bigge r im age 111 += S S′ f S′ M =− S f obje ct S S ’<0 f Physics 212 Le cture26, S 15 lide 15 Dive rging Le C ns: onside thecasewhe theshapeof thele is such that light rays paralle r re ns l t o theaxis of thele all dive but appe to com froma com on spot a distancef in ns rge ar e m front of t hele ns: f ront f Physics 212 Le cture26, S 16 lide 16 im is: age virtual upright sm r alle 111 += S S′ f S′ M =− S obje ct f im age f<0 S S ’<0 Physics 212 Le cture26, S 17 lide 17 Exe cutiveS m - Le s: um ary nse S> 2f 2f 2f > S> f re al inve d rte sm r alle re al re inve d rte bigge r virtual virtual upright bigge r conve rging f f > S> 0 111 += S S′ f S′ M =− S S >0 virtual virtual upright sm r alle dive rging f Physics 212 Le cture26, S 18 lide 18 I t’s always thesam : e 111 += S S′ f S′ M =− S You just haveto ke p thesigns straight: e Thesign conve ntions S positiveif obje is “upstre ” of le : positive ct am ns S : positiveif im is “downstre ” of le ’ age am ns f: positiveif conve rging le ns Physics 212 Le cture26, S 19 lide 19 Pre flight 2 By de finition, an im on thescre n (downstre of age e am t hele MUS BE REAL ns) T re e be though: m m r, 80 60 111 += s s′ f 111 =− ′fs s I f s < f, the s’ < 0: n virtual im age 40 20 0 Physics 212 Le cture26, S 20 lide 20 Pre flight 3 M =− s′ s s’ > 0 (re al) M < 0 (inve d) rte s’ < 0 (virtual) M > 0 (upright) 100 80 60 40 20 0 Physics 212 Le cture26, S 21 lide 21 Pre flight 5 BB Refraction cannot occur for the top half so the only thing seen will be that of the lower half of the object Only the top part of the arrow will not be seen as that part of the lens is responsible for the arrow head. The tape will block some of the light rays going onto the screen, but the other half of the lens will still refract the entire arrow onto the screen; just a little dimmer. 50 40 30 20 10 0 Physics 212 Le cture26, S 22 lide 22 obje ct im age C r top half of le ove ns Light fromtop of obje ct obje ct im age C r top half of le ove ns Light frombottomof obje ct What’s thePoint? Therays fromthebottomhalf still focus Theim is the , but it will bedim e !! age re mr Physics 212 Le cture26, S 23 lide 23 Pre flight 5 Physics 212 Le cture26, S 24 lide 24 air water θi θi 1.3 ? CaseI glass 1.5 ? CaseI I glass 1.5 BB I n CaseI light in air he toward a pie of glass with incide angle θ i ce nt Case air ads I n CaseI I , llight in wate he toward a pie of glass at thesam angle r ce e . Case ight wate ads sam I n which caseis thelight be m as it e rs theglass? nt ost nte I or I I or S e or am (A) (A) (B) (C) OK or NOT OK Physics 212 Le cture26, S 25 lide 25 air water θi glass θi θ2 θ2 CaseI I 1.3 glass 1.5 BB BB 1.5 CaseI I n CaseI light in air he toward a pie of glass with incide angle θ i ce nt Case air ads I n CaseI I , llight in wate he toward a pie of glass at thesam angle r ce e . Case ight wate ads sam I n which caseis theangleof re fraction thelarge ? st I or I I or S e or am (A) (A) (B) (C) n1sin(θ 1) = n2sin(θ 2) sin(θ 2)/sin(θ 1) = n1/n2 Physics 212 Le cture26, S 26 lide 26 air water θi glass θi θ2 θ2 CaseI I 1.3 glass 1.5 BB 1.5 CaseI I n CaseI light in air he toward a pie of glass with incide angle θ i ce nt Case air ads I n CaseI I , llight in wate he toward a pie of glass at thesam angle r ce e . Case ight wate ads sam I n which caseis thelight be m as it e rs theglass? nt ost nte I or I I or S e or am (A) (A) (B) (C) Theangleof re fraction in BI GGER for thewate – glass inte r rface : n1sin(θ 1) = n2sin(θ 2) sin(θ 2)/sin(θ 1) = n1/n2 Physics 212 Le cture26, S 27 lide 27 The foretheBEND ANGLE (θ 1 – θ 2) is BIGGER for air – glass inte re rface Pre flight 7 Therays arebe m fromair to glass than fromwate to glass nt ore r The fore thefocal le re , ngth in air is le than thefocal le ss ngth in wate r BB Wecan se this also fromLe ake Form e nsm r’s ula 50 40 30 20 10 0 nlens nair Physics 212 Le cture26, S 28 lide 28 C alculation Am agnifying glass is use to re thefineprint on a docum nt. The d ad e f ocal le ngth of thele is 10m . ns m At what distancefromthele m thedocum nt beplace in orde ns ust e d r t o obtain an im m age agnifie by a factor of 5 that is NOT inve d? d rte • Conceptual Analysis ns • Le Equation: 1/s + 1/s’ = 1/f • Magnification: M = -s’/s • Strategic Analysis onside natureof im (re or virtual?) to de rm re r age al te ine lation be e obje position and focal twe n ct •C point agnification to de rm obje position te ine ct • Usem Physics 212 Le cture26, S 29 lide 29 Am agnifying glass is use to re thefineprint on a docum nt. The d ad e f ocal le ngth of thele is 10m . ns m At what distancefromthele m thedocum nt beplace in orde ns ust e d r t o obtain an im m age agnifie by a factor of 5 that is NOT inve d? d rte BB BB Is the image real or virtual? (A) REAL (B) VI RTUAL A virtual im will beupright age A re im would beinve d al age rte h f h’ h’ h f Physics 212 Le cture26, S 30 lide 30 Am agnifying glass is use to re thefineprint on a docum nt. The d ad e f ocal le ngth of thele is 10m . ns m At what distancefromthele m thedocum nt beplace in orde ns ust e d r t o obtain an im m age agnifie by a factor of 5 that is NOT inve d? d rte BB BB How doe theobje distancecom s ct pare t o thefocal le ngth? (A) s< f Le ns Le e quation (B) s= f (C ) s> f 111 =− s′ f s s′ = Virtual I m o s’’ < 0 age ¸ s Re obje o s > 0 al ct ¸ C rging le o f > 0 onve ns ¸ fs s− f h’ h s’ s f s− f <0 Physics 212 Le cture26, S 31 lide 31 Am agnifying glass is use to re thefineprint on a docum nt. The d ad e f ocal le ngth of thele is 10m . ns m At what distancefromthele m thedocum nt beplace in orde ns ust e d r t o obtain an im m age agnifie by a factor of 5 that is NOT inve d? d rte s′ = fs s− f BB What is the magnification M in terms of s and f? (A) Le ns Le e quation: M= s− f f (B) M = f −s (C ) f M= −f s− f (D) M= f s− f Magnification Magnification e quation: 111 =− s′ f s s′ M =− s fs ′= s s− f h’ M= −f s− f h s’ s f Physics 212 Le cture26, S 32 lide 32 Am agnifying glass is use to re thefineprint on a docum nt. The d ad e f ocal le ngth of thele is 10m . ns m At what distancefromthele m thedocum nt beplace in orde ns ust e d r t o obtain an im m age agnifie by a factor of 5 that is NOT inve d? d rte M= −f s− f BB BB (A) 1.7m m (B) 6m m (C 8m )m (D) 40 m m (E) 60 m m M = +5 f = +10 mm M= −f s− f s= ( M − 1) f M h’ h s= 4 f = 8 mm 5 s′ = − sM = −40 mm f Physics 212 Le cture26, S 33 lide 33 Follow Up S upposewere placetheconve rging le with a dive ns rging le with focal ns le ngth of 10m . m If we still want to get an image magnified by a factor of 5 that is NOT inverted, how does the object sdiv compare to the original object distance sconv? (A) sdiv < sconv (B) sdiv = sconv (C) s > s div conv (D) sdiv doe e sn’t xist (D) EQUATIONS M= −f s− f s= f M −1 M PICTURES h h’ s f BB s’ M = +5 f = −10 mm 4 s = f = −8 mm 5 s negative s not real object Draw the rays: s’ will always be smaller than s Magnification will always be less than 1 Physics 212 Le cture26, S 34 lide 34 Follow Up S upposewere placetheconve rging le with a dive ns rging le with focal ns le ngth of 10m . m What is the magnification if we place the object at s = 8mm? M= −f s− f (A) 1 M (B) = 2 (C M = 5 ) (C (D) M = (D) 8 3 (E) M= 5 9 M= 4 5 EQUATIONS EQUATIONS M= −f s− f M =− PI C TURES s = 8 mm f = −10 mm −10 10 5 = = 8 − (−10) 18 9 h h’ f BB Physics 212 Le cture26, S 35 lide 35 ...
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This note was uploaded on 03/05/2011 for the course PHYS 212 taught by Professor Kim during the Spring '08 term at University of Illinois, Urbana Champaign.

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