12Plane Mirrors Using ray diagramming one finds that the image is 1. Upright2. Same size as the object3. Virtual
13Diffuse Reflection Video - Diffuse Reflection If successive elevations of a surface are no more than l/8 apart, thenthe surface is said to be polished at that wavelength.Most objects are seen by diffuse reflection.
14Diffuse Reflection Magnification of a surface Colored lines are for the purpose ofdistinguishing reflected rays fromincident rays.
15Something that is barely polished for red light would not be polished for blue light. Consider microwave satellite dishes.They are polished for microwaves but not for visible.The metal screen in a microwave oven serves what purpose?
16Reflection from Curved Surfaces (Concave shown here) Ray DiagrammingfPrincipal axisReflecting SurfaceThe law of specular reflection is still obeyed.
17Reflection from Curved Surfaces (Concave shown here) Ray DiagrammingfPrincipal axisReflecting SurfaceThe law of specular reflection is still obeyed.
18Demo - Coin MirageDemo – Deep Concave MirrorDemo - Make-up Mirror ImagesConcave mirrors can produce real inverted images that are magnified, diminished, or the same size as the object.Concave mirrors can produce virtual upright images that are magnified.
19More on MirrorsConvex mirrors always produce a diminished, upright, virtual image.Demo - Convex MirrorDemo - Two Perpendicular MirrorsDemo - Three Perpendicular MirrorsDemo – Road ReflectorsQuestion - Why is it hard to see at night after or during a rain?
21What type of mirror would you use to produce a magnified image of your face? (a) flat(b) concave(c) convex(d) you could use a concave or a convex mirror
22What is (are) the purpose(s) of the wire screen in the door of a microwave oven? (a) to absorb microwaves(b) to allow you to see what's cooking(c) to reflect microwaves(d) all of the above(e) only (b) and (c)
234. REFRACTIONFermat's principle can also explain refraction (remember the beach).Refraction of light is the bending of light as it passes obliquely from one medium to another.It is due to the different speeds of light in the two different media.
24Index of Refraction Index of refraction of a material equals the speed of light in a vacuum divided bythe speed of light in the material.
25Slide - Twinkling Cartoon Demo – Green Laser Refraction in an Aquarium Demo - Twinkling with LaserSlide - Twinkling Cartoon
26Video - Water Wave Refractions Video - "Broken" Pencil Refraction
27Because of atmospheric refraction, we have lingering, elliptical sunsets.SunEarthSun
28MirageCool airWarm airSurface of water?Highway Mirage
31An oar partially immersed in water appears "broken" because of (a) refraction(b) diffraction(c) polarization(d) interference(e) absorption
325. CAUSE OF REFRACTIONWhen light passes from one medium to another, its speed changes which in turn causes a bending of the light.Examples:Car running onto shoulder of roadLight passing from air into water
39DispersionDifferent frequencies are bent different amounts which causes a separation of white light into its constituent colors.This is the basic principle behind the operation of a prism. We say that a prism disperses the light.The higher frequencies interact most (slow down the most) and thus are bent the most.Demo - Aquarium Prism
42Picture - RainbowIndividual drops act as dispersers.The 42o coneDemo – Rainbow ModelA single eye can only see a small range of colors from a single raindrop.
43Secondary RainbowDouble rainbows are dimmer, higher, and have colors reversed. Link to picture.
44Green Flash Sun Earth Dispersion occurs causing multiple images of the sun.The last to set would be blue,but most of the blue has beenscattered which leaves green.
456. TOTAL INTERNAL REFLECTION Video - Laser Under WaterCritical angle is the angle where total internal reflection (TIR) begins.TIR is possible only when light is entering a medium of lesser index of refraction.Binoculars make use of TIR.
49A lingering sunset is (a) a looming effect (b) caused by an elliptical (oval) sun(c) due to atmospheric refraction(d) caused by reflections from the upper atmosphere
50When a beam of light emerges at a nonzero angle from water to air, the beam (a) bends away from the normal(b) continues in the same direction(c) bends toward the normal(d) changes frequency(e) slows down
517. LENSESLenses use refraction to form images.Demo - Fresnel Lens
53Imaging with a Convex Lens and passes through a pointcalled the focal point.is bent upon entering the lens.Arrow asObjectUpon exiting the lens it is bent againA ray parallel to the principal axissees animage here.fPrincipal AxisAn eye placed hereConvex LensA ray passing through the center of the lens is basically undeflected.This arrangement produces an inverted, real, diminished image.
54More Imaging With a Convex Lens is bent upon entering the lens.Upon exiting the lens it is bent againArrow asObjectand passes through a pointcalled the focal point.A ray parallel to the principal axisfPrincipal Axissees animage here.Convex LensAn eye placed hereA ray passing through the center of the lens is basically undeflected.This arrangement produces an upright, virtual, magnified image. It is a simple magnifying glass.Farsighted people use lenses similar to these.
56Imaging with a Concave Lens is bent upon entering the lens.Arrow asObjectUpon exiting the lens it is bent againA ray parallel to the principal axissuch that is appears to have comefrom a point called the focal point.fAn eye placed herePrincipal Axissees animage here.Concave LensA ray passing through the center of the lens is basically undeflected.This arrangement produces an upright, virtual, diminished image.Nearsighted people use lenses similar to these.
57Types of Lenses Convex lenses are positive converging lenses. PlanoConvexPlanoConcaveDoubleConvexDoubleConcaveConvex MeniscusConcave MeniscusConvex lenses are positive converging lenses.Concave lenses are negative diverging lenses.Nearsighted people use lenses similar to these.Farsighted people use lenses similar to these.
63One way to reduce the problem of spherical aberration in a positive lens is to join a negative lens to it to form a compound lens.(a) True(b) False
64If you wish to take a picture of your image while standing 5 ft in front of a plane mirror, for what distance should you set your camera to provide the sharpest focus?(a) 10 ft(b) 5 ft(c) 2.5 ft(d) it can't be done