In Young's double slit experiment light of wavelength $$500 \mathrm{~nm}$$ is used to form interference pattern. A uniform glass plate of refractive index 1.5 and thickness $$0.1 \mathrm{~mm}$$ is introduced in the path of one of the interfering beams. The number of fringes that will shift due to this is

Two narrow parallel slits illuminated by a coherent monochromatic light produces an interference pattern on a screen placed at a distance $$\mathrm{D}$$ from the slits. The separation between the dark lines of the interference pattern can be increased by

A monochromatic light of wavelength $$800 \mathrm{~nm}$$ is incident normally on a single slit of width $$0.020 \mathrm{~mm}$$ to produce a diffraction pattern on a screen placed $$1 \mathrm{~m}$$ away. Estimate the number of fringes obtained in Young's double slit experiment with slit separation $$0.20 \mathrm{~mm}$$, which can be accommodated within the range of total angular spread of the central maximum due to single slit.