In Young's double slit experiment, the screen is kept $1.6\mathrm{ }\mathrm{m}$ from the slits. The coherent sources are $0.032\mathrm{ }\mathrm{c}\mathrm{m}$ apart and fringes are observed on the screen. It is found that with a certain monochromatic source of light, the fourth bright fringe is situated at a distance of $1.06\mathrm{ }\mathrm{c}\mathrm{m}$ from the central fringe. The wavelength of the light used is