Lect26 - Physics 212 Lecture 26: Lenses Physics 212 Lecture...

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Physics 212 Lecture 26, Slide 1 Physics 212 Lecture 26: Lenses

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Physics 212 Lecture 26, Slide 2 Music Who is the Artist? A) Ramblin’ Jack Elliott B) Arlo Guthrie C) Pete Seeger D) Phil Ochs E) U. Utah Phillips Why? Last time I had to talk about 46 th anniversary of Arlo being arrested for litterin after Thanksgiving See the movie !!
Physics 212 Lecture 26, Slide 3 Your Comments “I felt like there were a lot of different versions of the magnification and lense equations shown on the prelecture. Which one should we use?” There are only two equations! They work for both lenses and mirrors You do have to know the CONVENTIONS “I just don't know what is virtual image? We can't see it right?” YOU CAN !! Just look in the mirror I want to discuss light diffraction and what happens when 2 or 3 converging lenses are placed in front of one another.?” “how does this apply to glasses?” We will discuss systems of lenses and the human eye in Lecture 28 “Did you know I was able to bend my self into a convergent lens and make myself completely clear so I could refract light to a focal point? I made a spectacle of myself.” Remember: Deadline for signing up for conflict is Tomorrow 10pm! “This stuff is so hard!!!!” “Thank you for easier concepts at the very end of the semester.” Always differing opinions?? “TURKEY TURKEY TURKEY is all i can think of. HAPPY Thanksgiving EVERYone!!!!!.” “If you put this comment on the power point I will give you a box of girl scout cookies. .. You know you want some thin mints.”

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Physics 212 Lecture 26, Slide 4 Refraction That’s all of the physics – everything else is just geometry! Snell’s Law n 1 sin( θ 1 ) = n 2 sin( θ 2 ) θ 1 θ 2 n 1 n 2
Physics 212 Lecture 26, Slide 5 air water glass glass Case I Case II In Case I light in air heads toward a piece of glass with incident angle θ i In Case II , light in water heads toward a piece of glass at the same angle. In which case is the light bent most as it enters the glass? I or II or Same (A) (B) (C) i i 2 2 1.5 1.5 1.3 The angle of refraction in BIGGER for the water – glass interface: n 1 sin( θ 1 ) = n 2 sin( θ 2 ) sin( θ 2 )/sin( θ 1 ) = n 1 /n 2 Therefore the BEND ANGLE ( θ 1 θ 2 ) is BIGGER for air – glass interface

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Physics 212 Lecture 26, Slide 6 Checkpoint 2 The rays are bent more from air to glass than from water to glass
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This note was uploaded on 03/12/2012 for the course PHYS 212 taught by Professor Kim during the Fall '08 term at University of Illinois, Urbana Champaign.

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Lect26 - Physics 212 Lecture 26: Lenses Physics 212 Lecture...

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