What kind of fringes do you expect to observe if white light is used instead of monochromatic light?

What kind of frings do you expect to observe if white light is used instead of monochromatic light?

How does the focal length of a convex lens change if monochromatic red light is used instead of monochromatic blue light?

Two coherent sources are placed 0.9 mm apart and the fringes are observed one metre away. The wavelength of monochromatic light used if it produces the second dark fringes at a distance of 10 mm from the central finge will be

Two coherent sources are placed 0.9 mm apart and the fringes are observed one metre away. The wavelength of monochromatic light used if it produces the second dark fringes at a distance of 10 mm from the central finge will be