Q:  What is the equivalent width of this weak absorption line?



             The width of the line is about 0.3 Angstroms, and depth
             is about 7000 units, so
     

                        area   =  (1/2) * (base) * (height)

                               =  (1/2) * (0.3 Ang) * (7000 units)

                               =  1,050 Angstrom*units.

            Since the height of the equiv-width rectangle must be about
                  10,000 units, its width must be

                                   1,050 Angstrom*units
                        width  =  ----------------------
                                   10,000 units


                               =   0.105 Angstroms