a
\({\text{I}}\,\, = \,\,{{\text{I}}_{\text{0}}}\,\,{\cos ^2}\,\,\left( {\frac{\delta }{2}} \right)\) જ્યાં 

\(\delta \,\, = \,\,k\,\,\left( {{r_2}\,\, - \,\,{r_1}} \right)\, = \,\) સંપટ બિંદુ આગળ કળા તફાવત 

 \(\therefore \,\,\frac{I}{{{I_0}}}\,\, = \,\,{\cos ^2}\,\,\left( {\frac{k}{2}\,\, \times \,\,\frac{\lambda }{6}} \right)\,\, = \,\,{\cos ^2}\,\,\left( {\frac{{2\pi }}{{2\lambda }}\,\, \times \,\,\frac{\lambda }{6}} \right)\,\)

\( = \,\,{\cos ^2}\,\,\left( {\frac{\pi }{6}} \right)\,\, = \,\,\frac{3}{4}\)