1. The problem statement, all variables and given/known data Light with wavelength 540 nm is split into two beams that travel along two paths. The difference between the path lengths is 3600 nm. What is the effective phase difference when the light recombines? 2. Relevant equations [itex]\phi[/itex] = (2pi/λ)*ΔL 3. The attempt at a solution It seems like a simple problem, I plug in 540 for λ and 3600 for ΔL but I'm not getting the right answer.