What will be the fringe pattern if wedge shaped air film is illuminated with white light?

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For normal incidence and air film, r=0 and μ = 1

Total path difference = 2tcosθ + λ/2

2tcosθ = (2n-1) λ/2………………………… maxima

2tcosθ= nλ……………………………………....minima

For every small angle of wedge,

As θ=0, cosθ=1

2t= (2n-1) λ/2

2tcosθ= nλ

i.e. every next bright fringe will occur for thickness interval of λ/2 each t=nλ/2, t=0, λ/2, 2λ/2, 3λ/2,…………….

i.e. every next dark fringe will occur for thickness interval of λ/2 each