(a) a double-slit experiment is set up using red light (l = 701 nm). a first order bright fringe is seen ata given location on a screen. what wavelength of visible light(between 380 nm and 750 nm) would produce a dark fringe at theidentical location on the screen? b) a new experiment is created with the screen at a distance of 2.1m from the slits (with spacing 0.12 mm). what is the distancebetween the second order bright fringe of light with l = 696 nm and the third order bright fringe oflight with l = 407 nm? (give theabsolute value of the smallest possible distance between these twofringes: the distance between bright fringes on the same side ofthe central bright fringe.)

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina.with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)