Ultraviolet (UV-A)
900 THz
UV-A radiation (315–400 nm).
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MeasuredPhysical measurement
Measured directly, or defined by a published standard.
This value is measured, or set by a published standard.
What the four labels meanChecked against sources September 27, 2026
About this number
UV-A radiation (315–400 nm). Causes skin tanning and aging. Not fully blocked by atmosphere.
Facts
- Frequency
- 900 THz
- Wavelength (electromagnetic wave)
- 333 nm
- Kind of statement
- Physical measurement
- Filed under
- Radio & light
Sources
- Definitions of visible light and ultraviolet
Where visible light and ultraviolet begin and end. The authorities do not agree exactly on the limits.
CIE International Lighting Vocabulary, terms 17-21-003 (visible radiation) and 17-21-008 (ultraviolet radiation). ISO 21348. BIPM, definition of the candela at 540 THz (555 nm).
View source: Definitions of visible light and ultraviolet