Waves with wavelengths between 400 mm and 10 nm are in the ultraviolet (UV) region of the electromagnetic spectrum.

Here's why:

* 400 mm is a very large wavelength and falls within the microwave region.

* 10 nm is a very small wavelength and falls within the extreme ultraviolet (EUV) region.

Therefore, the range between 400 mm and 10 nm covers the entire UV spectrum, which is further divided into:

* Near ultraviolet (NUV): 400 nm - 300 nm

* Middle ultraviolet (MUV): 300 nm - 200 nm

* Far ultraviolet (FUV): 200 nm - 100 nm

* Extreme ultraviolet (EUV): 100 nm - 10 nm

Let me know if you'd like more information about the UV spectrum!