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Thursday, July 10, 2008

Spectrum in a feather

Hold a large birdÌs feather just in front of one eye and look at a burning candle standing a yard away. The flame seems to be multiplied in an X-shaped arrangement, and also shimmers in the spectral colours.

The bending of light at the slits produces the appearance. Between the regular arrangement of feather sections (vanes and barbs) are narrow slits with sharp edges. The light is bent on passing through them, that is, it is refracted and separated into the spectral colours. Since you see through several slits at the same time, the flame appears many times.

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