KCET 2012 Physics Solved Paper

In Young's double slit experiment ,fringes of width β are produced on a screen kept at a distance of 1 m from the slit.When the screen is moved away by 5×10−2m,fringe width changes by 3×10−5m.The separation between the slits is 1×10−3m.The wavelength of the light used is ...........nm.