1. The problem statement, all variables and given/known data A beam of light of wavelength 600 nm passes through two slabs of material of identical thickness d= 1.40 micrometers, as shown in the figure. The slabs have different indices of refraction: n1= 1.41 and n2= 1.58. What is the phase difference between the two parts of the beam after it passes through the slabs? 2. Relevant equations [itex]\varphi[/itex] = (2[itex]\pi[/itex]/[itex]\lambda[/itex])*d*sin[itex]\theta[/itex] 3. The attempt at a solution I've calculated what I believe to be the difference in the number of wavelengths that fit in to each slab by applying the equation 2nt/ [itex]\lambda[/itex], where t is the given thickness of the slabs. The difference in question, I have calculated to be 0.793 m. My only question is how might I convert this difference into a phase difference in radians? My text gives the equation I have given under 'relevant equations', but I cannot figure out how to incorperate any angle or separation distance d, because the problem does not involve slits. The beam of light simply hits two blocks of differing indices of refraction at the same time? Can anyone offer any help? It would be much appreciated!