question_answer

In the figure shown in a YDSE, a parallel beam of light is incident on the slits from a medium of refractive index \[{{n}_{1}}\].The wavelength of light in this medium is\[{{\lambda }_{1}}\]. A transparent slab of thickness t and refractive index is put in front of one slit. The medium between the screen and the plane of the slits is \[{{n}_{2}}\]. The phase difference between the light waves reaching point O (symmetrical, relative to the slit) is

A) \[\frac{2\pi }{{{n}_{1}}{{\lambda }_{1}}}({{n}_{3}}-{{n}_{2}})t\]      

B) \[\frac{2\pi }{{{\lambda }_{1}}}({{n}_{3}}-{{n}_{2}})t\]

C) \[\frac{2\pi {{n}_{1}}}{{{n}_{2}}{{\lambda }_{1}}}\left( \frac{{{n}_{3}}}{{{n}_{2}}}-1 \right)t\]

D)        \[\frac{2\pi {{n}_{1}}}{{{\lambda }_{1}}}({{n}_{3}}-{{n}_{2}})t\]