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Bending Light, Fiber Optics and Optical Phenomena in Nature. The double rainbow!!!. Partial Reflection & Refraction. Sometimes when you look out a window you see outside and you see your reflection at the same time
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Bending Light, Fiber Optics and Optical Phenomena in Nature The double rainbow!!!
Partial Reflection & Refraction • Sometimes when you look out a window you see outside and you see your reflection at the same time • This depends on the angle of incidence as well as the relative indices of refraction of the two media. • Consider air to water: light traveling direction at the water (at 90º) will go straight through, however as the angle of incidence increase more light is reflected rather than passing straight through
Scuba diving • Because at large angle of incidence most of the light is reflected off the water when you are scuba diving light appears to be coming through a hole above you at the surface of the water
Water and refraction • Even though you know water is clear, you have difficulty seeing things farther away from you in the water. • This is because when you look farther away you increase the angle of incidence which causes more reflection and blocks your view into the water.
Critical angle & Total Internal Reflection • The angle of incidence that produces a refracted ray at an angle of 90º from the normal • It has the symbol <c • When the angle of incidence is greater than <c you get total internal reflection and all light is reflected back not passing through the medium.
Changing the direction of light • We can control light by putting the medium borders at large angles of incidence so that we get total reflection. • Bike reflectors and optical fibers are examples- with bike reflectors light will always bounce back the way it came
Fiber Optics Total internal reflection occurs all the way through the fibre so light travels quickly --telecommunications uses fiber optic cable to send information quickly --the medical field uses fiber optics in two ways, one to light up the area through endoscope (sending a tube into the body) second it uses fiber optics to send back images that the doctors can analyse. Non invasive
Sun dogs • Similar to rainbows, but instead of water droplets it is ice crystals refracting sunlight. • The most stunning sun dogs occur on cold clear mornings or evenings
Shimmering and mirages • Shimmering small scale • Mirage-large scale • Simmering is the apparent movement of objects in hot air over objects and surfaces • Mirages are the bending of light rays passing through layers of air that have extremely different temperatures. Since you are used to thinking that light travels in a straight line you interpret the origin of the light being on the ground when it is really the sunlight being refracted upwards.
Homework • Case study Pg 472 and 473 • Pg 475 # 1-7