A light wave of wavelength\[{{\lambda }_{0}}\]propagates from point A to point B. We introduce in its path a glass plate of refractive index n and thickness l. The introduction of the plate alters the phase of the plate at B by an angle\[\phi \]. If \[\lambda \] is the wavelength of lights on emerging from the plate, then

• A. \[\Delta \phi =0\]
• B. \[\Delta \phi =\frac{2\pi l}{{{\lambda }_{0}}}\]
• C. \[\Delta \phi =2\pi {{\ln }^{2}}\left( \frac{1}{\lambda }-\frac{1}{{{\lambda }_{0}}} \right)\]
• D. \[\Delta \phi =\frac{2\pi l}{{{\lambda }_{0}}}(n-1)\]