### Question

What is the wavelength of UVa, UVb, and UVc light measured in nanometers, and frequency (in Hz)?
Asked by: Richard M. Arnold, B.S.

According to multiple sources (NASA, FDA, and others) here are the wavelengths of the UVA, UVB and UVC regions:

UVA 400 nm - 320 nm
UVB 320 nm - 290 nm
UVC 290 nm - 100 nm

Note: nm means nanometer (400 nm = 400 x 10-9 meters or 0.0000004 meters)

As far as the frequency is concerned I will let you do the math: frequency = speed of light / wavelength.

You can read more about UVA, UVB and UVC regions of ultraviolet light and their impact on humans by visiting these web sites:

US FDA (Food and Drug Administration)

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'One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike - and yet it is the most precious thing we have.'

Albert Einstein
(1879-1955)