1. The problem statement, all variables and given/known data The figure shows the light intensity on a screen behind a double slit. The slit spacing is 0.20 mm and the wavelength of the light is 600 nm. What is the distance from the slits to the screen? This is the figure http://session.masteringphysics.com/problemAsset/1020631/6/jfk.Figure.17.P38.jpg 2. The attempt at a solution I have the answer there (attached thumbnail) from what the teacher provided, but I do not understand where 1/4 came from. Will someone please explain this to me? I am very confused. I am also confused on how the intensity diagram shown is used.