Lect25 - Physics 212 Le cture25 50 40 30 20 10 0 Confused...

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Unformatted text preview: Physics 212 Le cture25 50 40 30 20 10 0 Confused Avg = 3.0 Confident Physics 212 Le cture25, S 1 lide Music Who is the Artist? A) B) C) D) E) Miles Davis Oscar Peterson Gerry Mulligan John Coltrane Stan Getz Why? Just in a classic jazz mood, I guess I also was at a concert last Saturday when the also vocalist called Lush Life “obscure” hardly…… vocalist Physics 212 Le cture25, S 2 lide Physics 212 Le cture25 50 40 30 20 10 0 Confused Avg = 3.0 Confident Physics 212 Le cture25, S 3 lide Le start with a sum ary: t’s m 2 1 from n to n Physics 212 Le cture25, S 4 lide Thespe d of light in a m dium e The e is slowe than in e pty space r m : is sinceε 0 > ε vmedium = c / nmedium Physics 212 Le cture25, S 5 lide Pre flight 2 BB A B C What about thewavem bethesam on e r side??? ust e ithe 60 Obse rs in both m dia m agre on rve e ust e t hefre ncy of vibration of the que m cule ole s 50 40 30 20 10 0 Physics 212 Le cture25, S 6 lide Re ction fle Physics 212 Le cture25, S 7 lide Re fraction: S ll’s Law ne Physics 212 Le cture25, S 8 lide Think of a day at thebe ach… What's thefaste path to theball knowing st you can run faste than you can swim r ? This oneis be r tte Not thequicke route st … Physics 212 Le cture25, S 9 lide A B Tim fromA to B = t = l1/v1 + l2/v2 e Tim dt x1 x2 dx2 = + 2 2 2 2 dx1 v1 x1 + y1 v2 x2 + y2 dx1 -1 l l 1 = v1 1 x +y + v2 2 1 2 1 2 2 x2 + y2 dt x1 x2 =0= − dx1 v1l1 v2l2 x1 x =2 v1l1 v2l2 sin θ1 sin θ 2 = v1 v2 n1 sin θ1 = n2 sin θ 2 Physics 212 Le cture25, S 10 lide 10 Pre flight 6 80 S ll’s Law: ne n1sinθ 1 = n2sinθ 2 n de ase θ incre s cre s ase 60 40 20 0 Physics 212 Le cture25, S 11 lide 11 Total I nte Re ction rnal fle θ1 > θc Simulation Total I nte Re ction rnal fle Physics 212 Le cture25, S 12 lide 12 Pre flight 8 70 60 50 40 30 θ cle de nds on both n and n arly pe 20 10 0 Physics 212 Le cture25, S 13 lide 13 Inte nsity Anything looks likea m irror if light is just glancing off it. I f two m rials havethesam n ate e the its hard to te the apart. n ll m Physics 212 Le cture25, S 14 lide 14 Pre flight 4 70 60 50 40 30 20 10 0 Physics 212 Le cture25, S 15 lide 15 Polarization θ1 + θ 2 = 90 S ll’s Law: ne sin θ 2 = sin(90 − θ1 ) = cosθ1 n2 tan θ1 = n2 sin θ 2 = n2 cosθ1 = n1 sin θ1 n1 Physics 212 Le cture25, S 16 lide 16 A ball sits in thebottomof an othe rwisee pty tub at thefront of theroom m . S upposeN pe sit high e ople nough to se theball (N = e ). Physics 212 Le cture25, S 17 lide 17 A ball sits in thebottomof an othe rwisee pty tub at thefront of theroom m . S upposeN pe sit high e ople nough to se theball (N = e ). S upposeI fill thetub with wate but theball doe m . r sn’t ove Will m or le pe se theball? ore ss ople e A) Morepe will se theball ople e B) S e# will se theball am e A) Le pe will se theball ss ople e BB ?? θ θw A r no wat e water S ll’s Law: ray be away fromnorm going fromwate to air ne nt al r Physics 212 Le cture25, S 18 lide 18 Pre flight 10 BB Thelight would go out in all dire ctions, so only som of it e would beinte rnally re cte Thepe would se thelight fle d. rson e t hat e scape afte be re d r ing fracte d. 70 60 50 40 30 20 DRAW S OME RAYS 10 0 Physics 212 Le cture25, S 19 lide 19 Exam : Re ple fraction at wate r/air inte rface r’s • Dive illusion 97º Diver sees all of horizon refracted into a 97°cone θ1 = 90 n1 n1 1 sin θ 2 = sin 90 = = n2 n2 1.33 θ 2 = 48.5 Physics 212 Le cture25, S 20 lide 20 Exe rcise A m te stick lie at thebottomof a er s re ctangular wate tank of he 50cm r ight . re You look into thetank at an angleof 45o re rtical along a linethat 45 lativeto ve skim thetop e of thetank. s dge What is thesm st num r on the alle be rule that you can se ? r e rule 45o nwate = 1.33 r 50 cm 0 20 40 60 80 100 Conceptual Analysis: fracte at thesurfaceof thewate d r Light - Light is re Strategy: - De rm theangleof re te ine fraction in thewate r and e xtrapolatethis to thebottomof thetank. Physics 212 Le cture25, S 21 lide 21 Exe rcise A m te stick lie at thebottomof a er s re ctangular wate tank of he 50cm r ight . re You look into thetank at an angleof 45o re rtical along a linethat 45 lativeto ve skim thetop e of thetank. s dge What is thesm st num r on the alle be rule that you can se ? r e rule 45o nwate = 1.33 r 50 cm 0 20 40 60 80 100 If you shinea lase into thetank at an angleof 45o, what is the r re fracte angleθ R in thewate ? d r A) θ R = 28.3o S ll’s Law: ne B) θ R = 32.1o C) θ R = 38.7o BB nairsin(45) = nwatersin(θ R) sin(θ R) = nairsin(45)/nwater = 0.532 θ R = sin-1(0.532) = 32.1o Physics 212 Le cture25, S 22 lide 22 Exe rcise A m te stick lie at thebottomof a er s re ctangular wate tank of he 50cm r ight . re You look into thetank at an angleof 45o re rtical along a linethat 45 lativeto ve skim thetop e of thetank. s dge What is thesm st num r on the alle be rule that you can se ? r e rule What num r on therule doe thelase be hit ? be rs r am 45o θR nwate = 1.33 r 50 cm 0 20 40 60 80 100 d θ R = 32.1o A) 31.4 cm B) 37.6 cm tan(θ R) = d/50 C 44.1 cm ) BB d = tan(32.1) x 50cm= 31.4cm Physics 212 Le cture25, S 23 lide 23 Follow-Up Follow-Up A m te stick lie at thebottomof a er s re ctangular wate tank of he 50cm r ight . re You look into thetank at an angleof 45o re rtical along a linethat 45 lativeto ve skim thetop e of thetank. s dge 45o 50 cm nwate = 1.33 r 0 20 40 60 80 100 If thetank we half f ull of wate what num r would thelase hit? re r, be r (Whe full, it hit at 31.4 cm n ) A) 25 cm B) 31.4 cm C 32.0 cm ) D) 40.7 cm E) 44.2 cm BB Physics 212 Le cture25, S 24 lide 24 45o 45o θR nwate = 1.33 r 50 cm d = 31.4 cm d = 50 cm 80 100 0 20 40 60 80 100 50 cm 0 20 40 60 θ R = 32.1o 45o 50 cm θR 0 20 40 nwate = 1.33 r d = 40.7 cm 60 80 100 Physics 212 Le cture25, S 25 lide 25 25 cm+ (31.4/2) cm MorePractice Am onochrom ray e rs a slab with n1 = 1.5 at an angleθ b as shown atic nte θb TOP n=1 n1 = 1.5 BOTTOM θb n=1 BB (A) Total inte re ction at thetop occurs for all angle θ b, such that sinθ b < 2/3 rnal fle s (B) Total inte re ction at thetop occurs for all angle θ b, such that sinθ b > 2/3 rnal fle s (C) The is no angleθ b (0 < θ b < 90o) such that total inte re ction occurs at top. re rnal fle S ll’s law: ne n1 sin θ1 = n2 sin θ 2 nsinθ is “conse d” rve Ray e to air with sam angleas xits e it e re !! nte d Physics 212 Le cture25, S 26 lide 26 Follow-Up A ray of light m s through a m diumwith inde of re ove e x fraction n1 and is incide upon a se nt cond m rial (n2) ate at angleθ 1 as shown. This ray is the totally re cte at theinte n fle d rfacewith a third m rial (n3). Which ate state e m betrue m nt ust ? θ1 n1 n2 n3 θ1 (A) n3 < n1 (B) (C) n1 < n3 ≤ n2 n3 ≥ n2 I f n1 = n3 n1 n2 n3 BB θ1 Want large angleof re r fraction in n3 n3 < n1 Physics 212 Le cture25, S 27 lide 27 ...
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