In Young's double slit experiment,a glass plate is placed before one slit which absorbs half the intensity of light. Under this case:

In the setup shown in the figure,the two slits,$S_1$ and $S_2$,are not equidistant from the slit $S$. The central fringe at $O$ is then

To make the central fringe appear at the centre $O,$ a mica sheet of refractive index $\mu = 1.5$ is introduced. Choose the correct statement:

As shown in the figure,two point coherent sources $S_1$ and $S_2$ are placed at a small distance $d$ apart. The fringes formed on the screen will be .......

In a double-slit experiment,green light $(5303\,\mathring{A})$ falls on a double slit having a separation of $19.44\,\mu m$ and a width of $4.05\,\mu m$. The number of bright fringes between the first and the second diffraction minima is

The slits in a double-slit interference experiment are illuminated by orange light $(\lambda = 600 \ nm)$. $A$ thin transparent plastic sheet of thickness $t$ is placed in front of one of the slits. The number of fringes $(N)$ shifting on the screen is plotted versus the refractive index $\mu$ of the plastic in the graph shown. The value of $t$ is