MHTCET 13 May 2023 Shift 1 Solved Paper

In a biprism experiment, monochromatic light of wavelength ' λ ' is used. The distance between two coherent sources ' d ' is kept constant. If the distance between slit and eyepiece ' D ' is varied as D1,D2,D3&D4 and corresponding measured fringe widths are Z1,Z2,Z3 and Z4 then