1. The problem statement, all variables and given/known data The interference pattern on a screen 1.2 m behind a 710 line/mm diffraction grating is shown in Figure P22.45 (http://i137.photobucket.com/albums/q208/infinitbelt/p22-45alt.gif ), in which y1 = 52.3 cm and y2 = 107.6 cm. What is the wavelength of the light? 2. The attempt at a solution I believe that is a single slit diffraction grating. Thus the equation is a*sin(theta) = m(lambda), right? I then have sin(theta) = y/L Where do I go from there? I tried having two equations (one for y1 and one for y2) and setting them equal to one another by setting them individually equal to a. But that did not get me the right answer. Thanks!