1. The problem statement, all variables and given/known data A single slit forms a diffraction pattern with monochromatic light. The 4th minimum of the pattern occurs at an angle of 35 degrees from the central maximum. How many bright bands are on each side of the central maximum? 2. Relevant equations Number of minimum brightness bands = ((Width of slit)(sinθ))/λ Sinθ maxes out at sin90 = 1 3. The attempt at a solution I drew a pictures of the central maximum and then four bright spots on each side. I numbered the minimums one through four and then drew a line from the slit to the central maximum and another line from the slit to the center of the fourth minimum and labeled that angle 35 degrees. Now the problem doesn't give the width of the slit and it doesn't give the wavelength but does state that it's monochromatic. From the above formula it seems that the number of minimums is inversely proportional to the the wavelength so as the wavelength gets closer and closer to red, the number of minimums drops and as it gets closer to violet, it increases. The distance from the slit to the screen where these minimums and maximums are viewed, isn't give. I thought I could have used that length and the angle to figure out the width of the slit. I feel like there are more unknowns that I can deal with. Someone please help.