4. The width of the center peak (w) can be_ calculated using the following equation: 2AL W= , where 'a' is the width of the slit, 2 is the illumination wavelength, a and L is the distance from the foil to the viewing surface:.. Use this equation to determine the width of the slit that caused the diffraction pattern. Show your work. Single Slit Experiment Data Width of center peak (cm) 1.7 cm Width of slit for a single peak 2.5