Double-slit diffraction of blue and red light

(g) Double-slit diffraction patterns of long-wavelength red light (top) and short-wavelength blue light (bottom).

Blue light has a shorter wavelength than red. For a given doubleslit spacing d, the smaller value of λ/d for leads to smaller values of sin θ, and therefore to a more closely spaced set of diffraction fringes, (g)