1. The problem statement, all variables and given/known data Two waves of light in air, of wavelength 550 nm, are initially in phase. They then both travel through a layer of plastic as shown in the figure, with L1 = 4.00 μm, n1 = 1.40, L2 = 3.50 μm , and n2 = 1.60. What is their phase difference after they both have emerged from the layers, when they arrive at the same point? 2. Relevant equations N is the numbers of lemdas N1=L1*n1/λ N2=L2*n2/λ N in air = (L1-L2)/λ n(air)=1 3. The attempt at a solution N2+Nair-N2=0.909 but the correct answer is 5.71?????