Determine the optical path difference for the two waves A and B; both having vacuum wavele...

Determine the optical path difference for the two waves A and B; both having vacuum wavelengths of 500 nm, depicted in Fig. p.7.6; the glass (n = 1.52) tank is filled with water (n=1.33). If the waves start out in-phase and all the above numbers are exact, find their relative phase difference at the finishing line.