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Black Light. What is it? It is a portion of the Ultra-Violet Spectrum
that is invisible to our eyes. We can not distinguish it. However, when this
radiation impinges on certain materials visible light is emitted and this is
known as "fluorescence." Fluorescence is visible to the human eye, in that it
makes an object appear to "glow in the dark."
There are several sources of ultra-violet light. These sources are: the
sun, carbon arcs, mercury arcs, and black lights. In most cases, the production
of ultra-violet light creates a reasonable amount of heat.
Many materials exhibit the peculiar characteristic of giving off light
or radiant energy when ultra-violet light is allowed to fall upon them. This is
called luminescence. In most cases, the wave length of the light radiated is
longer than that of the ultra-violet excitation but a few exceptions have been
found.
The quantum theory attempts to explain this property by contending that
a certain outside excitation causes an electron to jump from one orbit to
another. It is then in an unstable environment causing it to fall back into its
original orbit. This process releases energy, and if it is in the visible part
of the ...
Brown J. Jed, Glenn Edward P., and O?Leary James W. 1998. Irrigating Crops with Seawater. Scientific American. ?? talks about the global problem of finding enough water and land for the world?s population to survive. An estimated 494.2 million acres of cropland is needed just to feed the tropics and subtropics for the next 30 years. H...
History of the Propeller The aircraft propeller looks like a simple mechanism to the uneducated individual. To the educated, an aircraft propeller represents the highest sophistication in aerodynamics, mechanical engineering and structural design. This report will touch on the history of the propeller, from early pioneers/experiments, advanceme...
Helium was discovered by a French astronomer named Pierre-Julius-Cesar Janssen. The French astronomer got evidence for the element during solar eclipse in 1868. He detected new lines in the solar spectrum. Later in 1895 Sir William Ramsay discovered it in clevite, a uranium mineral. Although it was discovered by Sir William Ramsay, the identi...
Cells can divide in three ways, binary fission, mitosis, and meiosis. Prokaryotes reproduce by binary fission in which the cell basically divides in half. The single, circular DNA, attached to the plasma membrane, duplicates, and the cell begins to grow. Continued growth of the cell separates the chromosomes, and eventually the plasma membrane a...
The ozone layer has begun to become 'thin.' It is often referred to as the 'hole in the ozone layer.' This problem has been created by human activities and specific chemicals that have been released. The chemicals released into the atmosphere are known as CFC's. These chemicals are released, begin to rise in the atmosphere, and eventually reach th...
