A double slit experiment uses a light source of wavelength 560 nm, where the slits are separated by a distance of 0.32 mm, and a screen is placed at 0.94 m behind the slits. The central maximum is located at the origin of the coordinate system. An unknown transparent material is used to cover one of the slits. Consequently, the light passing through the unknown material will be slowed down by 4.8 × 10^-16 s relative to the other slit because the light will travel slower in the other medium than air. Calculate what the phase difference of the waves leaving the slits due to the presence of the material will be.