Hello! I am stuck on a problem that seems so easy. The question is: Two slits are 0.143 mm apart. A mixture of red light (wavelength = 665 nm) and yellow-green light (wavelength = 565 nm) falls on the slits. A flat observation screen is located 2.29 m away. What is the distance on the screen between the third-order red fringe and the third-order yellow-green fringe? I solved for Theta for both red light and the yellow-green light. (m = 3) Theta = sin-1((m*lamda) / d) Red: Theta = sin-1((3 * 665e-9) / .143e-3) = .799 degrees Yellow-green: Theta = sin-1((3 * 565e-9) / .143e-3) = .679 degrees From there I solved for the distance and subtracted the two: y = L * tan theta Red: y = 2.29 * tan(.799) = 0.032m Yellow-green: y = 2.29 * tan(.679) = 0.027m I get an answer of 0.005m but the site says my answer is wrong. Any hints as to what I am doing wrong? Thank you for any help!!