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To
demonstrate this illusion make a simple device. Its two sides are shown
in Figure 1. |
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Figure 2 will help you to draw the exact patterns on the
both sides, or you may simply print them out and then cut them out. |
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Now glue together these rectangles or paste
them on a piece of cardboard of the same size. Just be careful to glue
the rectangles in the proper way. Make two holes and tie two short pieces
of string to the opposite edges. All this final process is shown in Figure
3 - just place the cursor on it. |
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Take the device in such a way that to hold
the pieces of string between your fingers as shown in Figure 4. Now turn
the pieces of string very quickly to make the rectangle turn. |
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What image will you see instead of the question
mark? |
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