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.

Assertion: Stationary wave is an example of interference.

Reason: Points of anti-nodes are points of constructive interference.

Assertion: Two coherent sources transmit waves of equal intensity $I_0$. Resultant intensity at a point, where path difference is $\frac{\lambda }{3}$ is also $I_0$.

Reason: In interference, resultant intensity at any point is the average intensity of two individual intensities.

Assertion: Fraunhofer diffraction occurs when all the rays passing through a narrow slit are approximately parallel to one another.

Reason: Fraunhofer diffraction pattern can be achieved by placing the screen far from the slit.

Assertion: In Young's double-slit experiment, often both the phenomena interference and diffraction are present.

Reason: Diffraction results due to the superposition of wavelets from different points of some wavefront.

Assertion: In the diffraction phenomenon, different maxima have different intensities.

Reason: In interference, different maxima have the same intensities.