question_answer

Two light waves having the same wavelength\[\lambda \] in vacuum are in phase initially. Then the first ray travels a path of length \[{{L}_{1}}\] through a medium of refractive index \[{{\mu }_{1}}\]. The second ray travels a path of length \[{{L}_{2}}\] through a medium of refractive index\[{{\mu }_{2}}\]. The two waves are then combined to observe interference effects. The phase difference between the two, when they interfere, is

A) \[\frac{2\pi }{\lambda }({{L}_{1}}-{{L}_{2}})\]

B) \[\frac{2\pi }{\lambda }({{\mu }_{1}}{{L}_{1}}-{{\mu }_{2}}{{L}_{2}})\]

C) \[\frac{2\pi }{\lambda }({{\mu }_{2}}{{L}_{1}}-{{\mu }_{1}}{{L}_{2}})\]

D) \[\frac{2\pi }{\lambda }\left[ \frac{{{L}_{1}}}{{{\mu }_{1}}}-\frac{{{L}_{2}}}{{{\mu }_{2}}} \right]\]