A Young’s Double slit experiment is performed using light of wavelength λ = 5000 Å, which emerges in phase from two slits 3 × 10^–7 m apart. A transparent sheet of thickness t = 1.5 × 10^–7 m is placed over one of the slits. The refractive index of the material of this sheet is μ = 1.17. The central maximum of the interference pattern appears at