Download Reflection and Refraction of Light in Physics 102: Lecture 17 and more Study notes Physics in PDF only on Docsity! Physics 102: Lecture 17, Slide 1 • Today’s Lecture will cover textbook sections 23.3, 8 Physics 102: Lecture 17 Reflection and Refraction of Light Physics 102: Lecture 17, Slide 2 Overview Reflection: Refraction: Absorption Flat Mirror: image equidistant behind Spherical Mirrors: Concave or Convex Flat Lens: Window Spherical Lenses: Concave or Convex T o d a y L a st T im e N e xt t im e θi θr θ1 θ2 n2 n1 θi = θr n1 sin(θ1)= n2 sin(θ2) Physics 102: Lecture 17, Slide 5 O I Mirror Equation 1 do + 1 di = 1 f c do di • do = distance object is from mirror: Positive: object _______ of mirror Negative: object _______ mirror • di = distance image is from mirror: • Positive: _______ image (__________ of mirror) • Negative: _______ image (__________ mirror) • f = focal length mirror: • Positive: _________ mirror • Negative: _________ mirror (coming soon) f Physics 102: Lecture 17, Slide 6 Preflight 17.3 The image produced by a concave mirror of a real object is: 1) Always Real 2) Always Virtual 3) Sometimes Real, Sometimes Virtual ACT: Concave Mirror 1) Close to mirror 3) Either close or far 2) Far from mirror 4) Not Possible Where in front of a concave mirror should you place an object so that the image is virtual? Physics 102: Lecture 17, Slide 7 O I Magnification Equation do do ho Angle of incidence di hi Angle of reflection o i o i d d h hm −=≡ o o d h =)tan(θ i i d h = di • ho = height of object: • Positive: • hi = height of image: • Positive: • Negative: • m = magnification: • Positive / Negative: same as for hi • < 1: • > 1: Physics 102: Lecture 17, Slide 10 3 Cases for Concave Mirrors Inside F•C F• Object Image •C F•Obje ct Image •C F•Obje ct Image Between C&F Past C Inverted Enlarged Real Upright Enlarged Virtual Inverted Reduced Real Physics 102: Lecture 17, Slide 11 O Convex Mirror Rays c 1) Parallel to principal axis reflects ______________. 2) Through f, reflects ______________________. #2 3) Through center. #3 Image is: Virtual or Real Upright or Inverted Reduced or Enlarged (always true for convex mirrors!) f #1 Complete the rays! Physics 102: Lecture 17, Slide 12 Solving Equations A candle is placed 6 cm in front of a convex mirror with focal length f=-3 cm. Determine the image location. Determine the magnification of the candle. If the candle is 9 cm tall, how tall does the image candle appear to be? Physics 102: Lecture 17, Slide 15 Light Doesn’t Just Bounce It Also Refracts! Reflected: Bounces (Mirrors!) Refracted: Bends (Lenses!) fdd i 111 0 =+ θi θr θ1 θ2 n2 n1 θi = θr n1 sin(θ1)= n2 sin(θ2) Physics 102: Lecture 17, Slide 16 v = c n Speed of light in medium Index of refraction Speed of light in vacuum n > 1 v < c so Index of Refraction 186,000 miles/second: it’s not just a good idea, it’s the law! always! Physics 102: Lecture 17, Slide 17 Snell’s Law n1 n2 When light travels from one medium to another the speed changes v=c/n, but the frequency is constant. So the light bends: n1 sin(θ1)= n2 sin(θ2) θ1 θ2 1) n1 > n2 2) n1 = n2 3) n1 < n2 Preflight 17.6 Compare n1 to n2.
