Unpolarised light of intensity 32 Wm$$^{-2}$$ passes through the combination of three polaroids such that the pass axis of the last polaroid is perpendicular to that of the pass axis of first polaroid. If intensity of emerging light is 3 Wm$$^{-2}$$, then the angle between pass axis of first two polaroids is ______________ $$^\circ$$.
A beam of light consisting of two wavelengths $$7000~\mathop A\limits^o $$ and $$5500~\mathop A\limits^o $$ is used to obtain interference pattern in Young's double slit experiment. The distance between the slits is $$2.5 \mathrm{~mm}$$ and the distance between the plane of slits and the screen is $$150 \mathrm{~cm}$$. The least distance from the central fringe, where the bright fringes due to both the wavelengths coincide, is $$n \times 10^{-5} \mathrm{~m}$$. The value of $$n$$ is __________.
As shown in the figure, in Young's double slit experiment, a thin plate of thickness $$t=10 \mu \mathrm{m}$$ and refractive index $$\mu=1.2$$ is inserted infront of slit $$S_{1}$$. The experiment is conducted in air $$(\mu=1)$$ and uses a monochromatic light of wavelength $$\lambda=500 \mathrm{~nm}$$. Due to the insertion of the plate, central maxima is shifted by a distance of $$x \beta_{0} . \beta_{0}$$ is the fringe-width befor the insertion of the plate. The value of the $$x$$ is _____________.
