A narrow slit 0.072 mm wide is illuminated with monochromatic light, and a diffraction pattern is observed on a screen 4.0 m from the slit. The width of the central maximum of this pattern is 2.8 cm. What is the wavelength of the incident light? How would this pattern change, if at all, if the slit width were increased to 0.16mm? What if the whole set-up were under water?