in a double-slit experiment with slit separation d = 0.90 mm , the m = 9 bright spot is at a height y = 6.5 cm above the central maximum.Part AIf the viewing screen is a distance L = 1.5 m from the two slits, what is the extra distance, Δr=r2−r1, traveled by the light coming from the lower slit (as shown in the figure)? (Figure 1)Δr = nmPart BWhat was the wavelength of light used in this experiment?λ = nm