In Young's double slit experiment, carried out with light of wavelength $$5000~\mathop A\limits^o$$, the distance between the slits is $$0.3 \mathrm{~mm}$$ and the screen is at $$200 \mathrm{~cm}$$ from the slits. The central maximum is at $$x=0 \mathrm{~cm}$$. The value of $$x$$ for third maxima is __________ $$\mathrm{mm}$$.

Two wavelengths $$\lambda_1$$ and $$\lambda_2$$ are used in Young's double slit experiment. $$\lambda_1=450 \mathrm{~nm}$$ and $$\lambda_2=650 \mathrm{~nm}$$. The minimum order of fringe produced by $$\lambda_2$$ which overlaps with the fringe produced by $$\lambda_1$$ is $$n$$. The value of $$n$$ is _______.

Two waves of intensity ratio $$1: 9$$ cross each other at a point. The resultant intensities at that point, when (a) Waves are incoherent is $$I_1$$ (b) Waves are coherent is $$I_2$$ and differ in phase by $$60^{\circ}$$. If $$\frac{I_1}{I_2}=\frac{10}{x}$$ then $$x=$$ _________.