In a Young's double-slit experiment, the separation between two slits is $d$ and wavelength of light is $\lambda$. The intensity of light falling on slit $1$ is four times the intensity of light falling on slit $2$. Find the correct choices.
 

In a Young's double-slit experimental arrangement shown here, if a mica sheet of thickness $t$ and refractive index $\mu$ is placed in front of the slit $S_1$ then, the path difference $\left(S_{1}P-S_{2}P\right)$,

In Young's experiment, monochromatic light is used to illuminate the two slits $A$ and $B$. Interference fringes are observed on a screen placed in front of the slits. Now, if a thin glass plate is placed normally in the path of the beam coming from the slit, then