1. The problem statement, all variables and given/known data I am to calculated the wavelength of the laser I shone through different slit patterns to create diffraction patters on a screen. For the single slit diffraction, Data: xm is the distance from the central image to the mth minimum. x1 0.008 x2 0.015 x3 0.023 x4 0.030 x5 0.037 The distance L from the grating to the screen is 1.865 The slit width a is 0.00016 2. Relevant equations asinø=my Equation for minima for a single slit system 3. The attempt at a solution I graphed sinø verses m; in other words: sinø = (y/a)m So the slope of that graph is y/a. So the slope times a is y. [[ I calculated sinø using (xm)/( ((xm^2)+(L^2))^(1/2) ) ]] The slope, I found using Excel, of the graph of sinø vs m, is 0.003. So lambda, y, should be y = 0.003*0.00016 = 4.8*10^-7 This is a wavelength of 480nm. The literature value is close to 640nm. My results for the double-slit is even more off, giving me a calculated wavelength of 2000nm - which is obviously wrong because I wouldn't have been able to see that. What am I doing wrong?