1) In the Young's double-slit experiment using a monochromatic ;light of wavelength λ the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is A) (2n+1)λ2 B) (2n+1)λ4 C) (2n+1)λ8 D) (2n+1)λ16 Answer: Option BExplanation:I=Imaxcos2ϕ2 ...............(i) Given, I=Imax2.........(ii) From Eqs( i) and (ii) , we have ϕ=π2,3π2,5π2 Or path difference , △x=(λ2π).ϕ ∴ △x=λ4,3λ4,5λ4,.....(2n+14)λ