WBJEE 2025 Physics and Chemistry Papers

Fringe positions are given by the single-slit minima condition
asin‌θ=mλ‌‌(m=±1,±2,...)
so the angular fringe spacing scales as ∆θ∼λ∕a. Blue light has a smaller wavelength than red, hence its diffraction fringes are closer together (narrower angular width).