why did filling the glass with water change the arrow?

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Anastasia.fr.1

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I filled up a glass with water, then i drew a arrow sign pointing to the left on a piece of paper. When i put the arrow sign behind the glass of water, the arrow pointed to the right instead of the left.


why and how did this happen [?] [?] [?] [?]

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Offline graham.d

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why did filling the glass with water change the arrow?
« Reply #1 on: 05/07/2008 11:47:21 »
The cylinder of water in the glass acts as a lens - a cylindrical lens rather than a normal spherical lens so the effect will be only horizontal not vertical. It is hard to explain without showing a drawing showing how the light rays are refracted objects beyond the effective focal length will be inverted. If you bring your arrow close to the glass it will not be inverted but magnified.

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Anastasia.fr.1

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why did filling the glass with water change the arrow?
« Reply #2 on: 05/07/2008 15:10:25 »
thank you for your answer.