In this applet we determine the ionization energy of an atom from a graphical analysis of the convergence of lines in its spectrum.

Plot the wavenumber data against 1 / n^{2}. The intial value of n is unspecified
(we assume that the data points refer to successive integral values of n); but the correct
value can be determined by making several choices
(e.g., n_{i} = 1,2..5,6; n_{i} = 2,3..6,7; n_{i} = 3,4..7,8)
and selecting the one that leads to a straight line
(i.e., has a **correlation (r)** close to + or - 1.0 and minimizes the **standard error**).