Ultra Violet light


Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency of approximately 30 PHz) to 400 nm (750 THz), shorter than that of visible light but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.

There are 3 kinds of UV light depending on the wavelength : UVA, UVB and UVC. UVA is the closest to the visible light. It fades colors in plastics and clothes and contributes to smog. UVB (315-290) is mostly absorbed by the ozone laqyer in the atmosphere but the ammount that makes it through can damage the DNA molecules in living cells and cause sunburn. UVC is very dangerous but it is all blocked by the earth’s atmosphere.

UV light can be seen but can be detected when:
  • Some chemicals absorb UV light and then re-emit the energy as visible light.

  • The visible light disappears when the UV source is removed.

Some of the uses of UV light are as follows:
  • To kill bacteria, attract bugs, detect forgeries, detect bodily fluids in forensic light.

  • UV lamps used to detect fake dollar bills ( $5 and above ).

Some of the dangers of UV light are as follows:
  • UV light have more energy than visible light and can damage living cells. It damages tissues in our eyes and cause cataracts.

How to prevent being affected by UV light:
  • By use of sunscreen that blocks UVB light which could cause sunburn to the skin.

  • By use of eye epectacles with photochromic lenses which will protect you from direct sunlight and other sources of ultraciolet light.

Authored by:
Winfred Nakamanya
RN., Eye Specialised Nurse
June 2020

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