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Description:
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The observation that a stick partially
plunged into a pool of clear water
looks as if it is bent (figure 1) probably
goes back to time immemorial. The
more sophisticated interpretation of
this observation as being due to the
bending of light rays on passing from
one medium (air) to another (water), as
well as the law governing the angles
which the rays make in the two mediums
relative to a normal drawn perpendicular to
the surface separating them (figure 2), has been
discovered several times throughout history – first
by the Arab, Ibn Sahi, in 984 AD, then by Thomas
Harriot in 1602, then by Willebrord Snellius or
Snell (figure 3) in 1621, and lastly by René Descartes
(figure 4) in 1637. |
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