In the adjacent diagram, $\mathrm{CP}$ represents a wavefront and $\mathrm{AO}$ and $\mathrm{BP}$, the corresponding two rays. Find the condition of $\theta$ for constructive interference at $\mathrm{P}$ between the rays $\mathrm{BP}$ and reflected ray $\mathrm{AOP}$

Two coherent sources separated by distance $d$ are radiating in phase having wavelength $\lambda$. A detector moves in a big circle around the two sources in the plane of the two sources. The angular position of $n=4$ interference maxima are given as

Two coherent light sources $\mathrm{A}$ and $\mathrm{B}$ are at a distance $3 \lambda$ from each other $(\lambda =$ wavelength $)$. The distances from $\mathrm{A}$ on the $x$ -axis at which the interference constructive are

Figure shows a standard two slit arrangement with slits $S_1, S_2, P_1, P_2$ are the two minima points on either side of $P$ (figure).

At $P_2$ on the screen, there is a hole and behind $P_2$ is a second $2$-slit arrangement with slits $S_3, S_4$ and a second screen behind them.

Assertion: If a glass slab is placed in front of one of the slits, then fringe width will decrease.

Reason: Glass slab will produce an additional path difference.

Assertion: Interference shows wave nature of light.

Reason: Photoelectric effect proves particle nature of light.

Assertion: If wavelength is of the order of distance between the slits, then fringe size is large.
Reason: Fringe width is given by, $w=\frac{\lambda D}{d}$.

Assertion: In Young's double slit experiment, ratio $\frac{I_{\max }}{I_{\min }}$ is infinite.

Reason: If width of any one of the slits is slightly increased, then this ratio will decrease.