angstrom unit angstrom unit /ˈæŋstrəm ˈjuːnɪt/

noun

1. A metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation  ( angstrom , angstrom unit , A )
   a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
    Light has a wavelength in the range of 400–700 nm.
   Light has a wavelength in the range of 400–700 nm.