Ultraviolet Waves
They are often known as black light, which is
invisible to the human eye. However, when it falls on certain surfaces, it will induce
them to emit visible light.
That portion of the electromagnetic
spectrum adjacent to the short wavelength, or violet, end of the visible light range,
is called ultraviolet radiation (UV).
The wavelengths of ultraviolet (UV) radiation start a bit shorter than
visible light and extend to low-energy X rays. UV wavelengths usually start a bit shorter
than visible light extending eventually to low-energy X rays. Emittion is from
high-temprature surfaces such as the sun. The UV spectrum is usually divided into 2
regions : near, or soft, ultraviolet which is nearer to the visible spectrum, with
wavelengths of 200 to 380 nanometers; and far, or hard, ultraviolet, with wavelengths of
10 to 200 nanometers. (One nanometer is equal to 0.00000000001 centimeter.) The atoms of
many elements radiate energy in the ultraviolet range.
Scientists began to realise the effect of UV light on
silver chloride in early 1801 and ever since UV photographs have been made. They provide a
strikingly different view of what is expected to be seen by the human eye.
Only until recently years that the drastic
effects of UV rays on living organisms are finally discovered. Before we go into that, the
human body also needs UV rays at a considerable amount to manufacture and regulate the
production of certain vitamins and chemicals. For example, exposure to longer-wavelength
UV radiation is necessary for the production within the body of vitamin D, a substance
that helps promote and maintain proper bone development. It also causes the production of
melanin, a chemical in the skin , resulting in a sun tan.
Harmful effects
Sunburn, suntan, and progressive adaptation
to heavier doses
Induced thickening of the skin, more rapid
skin aging, and a much higher frequency of skin disorders, including cancer, particularly
in fair-skin people.
An increase in skin temperature, skin
respiration, and skin cholesterol.
A dip in pain sensitivity, perspiration, and
mineral levels in the body's tissues.
