Q5. A diffraction pattern is observed in the focal plane of a lens of focal length 5 m which lies behind a double slit illuminated by light of wavelength 5 × 107 m. The spacing between the centres of successive bright fringes is 4 mm. However to either side of the central fringe one finds the fifth, tenth....fringes are extremely faint. Find the width of the slits and their distance apart.

Q5. A diffraction pattern is observed in the focal plane of a lens of focal length 5 m which lies behind a double slit illuminated by light of wavelength 5 × 107 m. The spacing between the centres of successive bright fringes is 4 mm. However to either side of the central fringe one finds the fifth, tenth....fringes are extremely faint. Find the width of the slits and their distance apart.