મહતમ તીવ્રતા માટે \(cos\,\,\theta \,\, = \,\,1\,\, \Rightarrow \,\,I\) મહતમ \(  = \,\,\,{\left( {\sqrt {{I_1}} \,\, + \,\,\sqrt {{I_2}} } \right)^2}\)

ન્યૂનતમ તીવ્રતા માટે \(cos\,\,\theta \,\, = \,\,\, - 1\,\,\,\, \Rightarrow \,\,\,\,I\) ન્યૂનતમ \( = \,\,{\left( {\sqrt {{I_1}}  - \sqrt {{I_2}} } \right)^2}\)

\(I\)ન્યૂનતમ/\(I\)મહતમ \( = \,\,\,{\left( {\frac{{\sqrt {{I_1}} \,\, + \,\,\sqrt {{I_2}} }}{{\sqrt {{I_1}}  - \sqrt {{I_2}} }}} \right)^2}\,\,\, = \,\,\,{\left( {\frac{{\sqrt {\frac{{{I_1}}}{{{I_2}}}}  + 1}}{{\sqrt {\frac{{{I_1}}}{{{I_2}}}}  - 1}}} \right)^2}\,\)

\(\, = \,\,\,\,{\left( {\frac{{\sqrt {81}  + 1}}{{\sqrt {81}  - 1}}} \right)^2}\,\, = \,\,\,{\left( {\frac{{9 + 1}}{{9 - 1}}} \right)^2}\,\, = \,\,\frac{{100}}{{64}}\,\,\, = \,\,\,\frac{{25}}{{16}}\)