opacity

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Ahura Mazda - relief of the Zoroastrian god Ahura Mazda at the ancient ruins of Persepolis in Iran. Also known as Ormazd Zoroastrianism,

Which Religion Is the Oldest?

Marriage. A couple getting married during a church wedding ceremony. (religion, ceremony, bride, groom)

The Seven Sacraments of the Roman Catholic church

Groups of depositors in front of the closed American Union Bank, New York City. April 26, 1932. Great Depression run on bank crowd

Causes of the Great Depression

New Zealand. Political/Physical map. Includes locator.

Where Is “Old Zealand”?

July, 2006, Launch of Space Shuttle Discovery STS-121. See attached for full caption information.

Will Light-Speed Space Travel Ever Be Possible?

African Americans demonstrating for voting rights in front of the White House as police and others watch, March 12, 1965. One sign reads, "We demand the right to vote everywhere." Voting Rights Act, civil rights.

Timeline of the American Civil Rights Movement

Titanic infographic. The 30th anniversary of its discovery is September 1, 2015. SPOTLIGHT VERSION.

Timeline of the Titanic’s Final Hours

opacity

of matter

Learn about this topic in these articles:

glass

In industrial glass: Transparency, opacity, and colour
Because electrons in glass molecules are confined to particular energy levels, they cannot absorb and reemit photons (the basic units of light energy) by skipping from one energy band to another and back again. As a consequence, light energy travels through glass…
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paper

In papermaking: Optical properties
Opacity is one of the most desired properties of printing and writing papers. Satisfactory performance of such papers requires that there be little or no “show-through” of images from one side of the sheet to the other. Satisfactory opacity in printing papers requires that white…
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