What is the wavelength of UV and IR?

Wavelength of UV and IR

Ultraviolet (UV) and Infrared (IR) light are both parts of the electromagnetic spectrum, which includes a range of wavelengths from gamma rays to radio waves. Visible light, which is the light detectable by the human eye, lies between UV and IR light in this spectrum.

Ultraviolet (UV) Light

UV light has a shorter wavelength than visible light and is, therefore, invisible to humans. It is categorized into three main types based on its wavelength range:

  • UVA: 315 to 400 nm (nanometers)
  • UVB: 280 to 315 nm
  • UVC: 100 to 280 nm

UVA is the closest to visible light and is the least harmful. It is typically associated with skin aging. UVB, with medium wavelengths, can cause skin reddening and sunburn. UVC has the shortest wavelengths and can be very harmful due to its energy, but it is absorbed by the Earth's atmosphere and does not reach the surface.

Infrared (IR) Light

Infrared light has longer wavelengths than visible light and, similar to UV, is not visible to the human eye. IR radiation is commonly associated with heat, as objects at room temperature or above will emit radiation in this wavelength range. Infrared can be divided into bands:

  • Near-infrared (NIR): 0.75 to 1.4 µm (micrometers)
  • Short-wavelength infrared (SWIR): 1.4 to 3 µm
  • Mid-wavelength infrared (MWIR): 3 to 8 µm
  • Long-wavelength infrared (LWIR): 8 to 15 µm
  • Far infrared (FIR): 15 to 1,000 µm

Near-infrared is used in remote controls and fiber optic communication, while thermal imaging and heat-seeking missiles typically use mid and long-wavelength infrared. Far infrared is further from the visible spectrum and closer to the microwave range, used, for example, in far infrared saunas.

The electromagnetic spectrum's UV and IR wavelengths are both instrumental in various technologies and natural processes. While UV light helps in the synthesis of vitamin D and is used in sterilization processes, IR radiation is significant for thermal imaging and heating applications. Understanding their properties and applications is crucial in fields such as optics, communications, and environmental science.

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