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Transparent Objects
Name: Bill
Status: educator
Age: N/A
Location: N/A
Country: N/A
Date: Around 1999
Question:
Why are some things like glass clear, in that we can see
through them, while other obects like wood and not clear.
Replies:
A material needs to have two properties to be clear. First, it must not
absorb visible wavelengths of light. This is necessary, but not
sufficient. Materials such as snow and paper do not directly absorb light,
but they aren't clear. The second property they need is to be uniform in
composition. Paper and snow contain lots of air pockets; when light
crosses from one material (ice or cellulose) to the other (air), it
scatters. That's why you can't see through snow, or milk, or fog, even
though they don't appreciable absorb light.
Richard E. Barrans Jr., Ph. D.
Chemistry Division
Argonne National Laboratory
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Update: February 2012
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