In Young's double slit experiment, the distance between screen and aperture is 1 m . The slit width is 2 mm . Light of $6000 \mathop {\rm{A}}\limits^{\rm{o}}$ is used. If a thin glass plate ( $\mu=1.5$ ) of thickness 0.04 mm is placed over one of the slits, then there will be a lateral displacement of the fringes by

In Young's double slit experiment, when light of wavelength 600 nm is used, 18 fringes are observed on the screen. If the wavelength of light is changed to 400 nm , the number of fringes observed on the screen is

In Young's double slit experiment, for the $n$th dark fringe ( $\mathrm{n}=1,2,3 \ldots$ ) the phase difference of the interfering waves in radian will be

In Young's double slit experiment, the intensity on screen at a point where path difference is $\frac{\lambda}{4}$ is $\frac{K}{2}$. The intensity at a point when path difference is ' $\lambda$ ' will be