\(\therefore \,\bar v = R{Z^2}\left[ {\frac{1}{{n_i^2}} - \frac{1}{{n_f^2}}} \right] = R\left[ {\frac{1}{{{8^2}}} - \frac{1}{{{n^2}}}} \right]\)

or, \(\bar v = {R_H}\left( {\frac{1}{{64}} - \frac{1}{{{n^2}}}} \right)\)

\( = \frac{{{R_H}}}{{64}} - \frac{{{R_H}}}{{{n^2}}}\)

\(\bar v =  - {R_H}\left( {\frac{1}{n^2}} \right) + \frac{{{R_H}}}{{64}}\)

\(\therefore \,y = mx + c\)

Slope \(= -R_H\)