1. The problem statement, all variables and given/known data Two slits separated by a distance of d = 0.12mm are located at a distance of D = 780mm from a screen. The screen is oriented parallel to the plane of the slits. The slits are illuminated by a coherent light source with a wavelength of lambda = 549E-6 mm. The interference pattern shows a peak at the center of the screen (m=0) and then alternating minima and maxima. 7. [1pt] What is the pathlength difference between the two waves from the two slits at the first (m=1) maximum on the screen? 2. Relevant equations d*sintheta = m*wavelength sintheta = y(dist bt two maxima) / D(distance to screen) 3. The attempt at a solution I'm really confused about what the "pathlength difference" refers to. It doesn't specify it in the book. I know the angles take different paths to get to the same point because of the distance inbetween them, but is it asking for an angle??? I solved the problem for y using the above equations, and at the first maxima (m=1), y(distance between the two maxima) is 0.0036m. But I don't know where to go from there?