How to use refraction to make glass disappear!
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Because glass and vegetable oil have nearly the same optical density, light passing through glass and oil does not bend. Remember, for refraction or bending to occur, the light has to pass from one transparent medium to another of different optical density.
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Cool Refraction caused by the Earth's Atmosphere
Where the star appears compared to where it actually is is also due to refraction through the air in the Earth's atmosphere. A star twinkles (technically known as stellar scintillation) because the optical density of the air at the upper levels of the atmosphere is different from that at the lower levels. But to add excitement to the refraction, winds that blow mix the air and change the densities, causing the refraction to "change with the winds." CLICK here for more information!
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Combining Refraction and Reflection to Make a Rainbow
Rainbows are an optical illusion caused by light striking a lens (such as a raindrop), refracting, then reflecting and then refracting again. White light is actually a combination (or addition) of all the colors of the rainbow, each traveling at a slightly different speed (or wavelength). When they enter the lens, they slow down, but because each enters at a different speed, they slow down to different speeds. Thus, they bend at slightly different angles. When they are reflected within the raindrop and are refracted again, they speed up to different speeds, and bend again, causing the colors to split.
Double rainbows are caused by light refracting, then reflecting within the raindrop twice and then refracting outward toward your eye. |
Rainbow physics is pretty complicated. The top video shows a simplified version of the explanation. The bottom video shows a college-level explanation (for those of you who wish to brave the math and physics!)
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