A thin glass plate of thickness \[\frac{2500}{3}\lambda (\lambda \] is wavelength of light used) and refractive index \[\mu =1.5\] is inserted between one the slits and the screen Yongs double slit experiment. At a point on the screen equidistant from the slits, the ratio of the intensities before and after the introduction of the glass plate is: [JEE ONLINE 25-04-2013]