Physics Photo of the Week

Warren Wilson College

Rectangular Kaleidoscope


Omar Barnaby noticed this strange effect in the physics lab.  While looking through a hollow, rectangular meter stick, he noticed the interesting symmetrical pattern of repeated reflections in the side walls of the pipe.  See photo below to see the general shape of the hollow meter stick.  The smooth interior walls of the extruded plastic act as mirrors which reflect the light entering the tube from the far end.  Since the mirrors line the opposite walls of the tube, multiple reflections occur, presenting a repeated pattern of the central bright rectangle of light in 4-fold symmetry.  Kaleidoscopes are usually manufactured with internal mirrors of 30, 45, or 60 degrees to give the typical multiple "rosette" symmetries.
The photo at right shows the usual appearance of the hollow rectangular meter stick, made of extruded plastic.  Looking through the pipe at the wall produced the kaleidoscope effect.


Physics Photo of the Week is published every Friday during the academic year by Donald F. Collins.  If anyone has any unusual photos of interesting weather patterns, shadow effects, optical effects, the physics department would welcome them to consider for publication.

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Donald F. Collins