In Young’s double slit experiment, red light of wavelength 6000$\stackrel{\circ }{\mathrm{A}}$ is used and the nth bright fringe is obtained at a point ‘P’ on the screen. Keeping the same setting, the source of light is replaced by green light of wavelength 5000$\stackrel{\circ }{\mathrm{A}}$ and now (n+1)^th bright fringe is obtained at the point P on the screen. The value of ‘n’ is $\_\_\_\_\_$