$A$ laser beam is used for surgery because it can be...

In the given figure,light of intensity $I$ is incident on a glass slab at point $A$ at an angle of incidence $\theta_1$. It undergoes partial reflection and partial refraction. At each reflection,$25\%$ of the incident energy is reflected. If interference occurs between the rays $AB$ and $A'B'$,then $I_{max}/I_{min} = \dots$ (in $: 1$)

The figure shows $P$ and $Q$ as two equally intense coherent sources emitting radiations of wavelength $20 \, m$. The separation $PQ$ is $5.0 \, m$ and the phase of $P$ is ahead of the phase of $Q$ by $90^{\circ}$. $A, B,$ and $C$ are three distant points of observation equidistant from the mid-point of $PQ$. The intensity of radiations at $A, B,$ and $C$ will bear the ratio:

Assertion: The colour of the green flower seen through red glass appears to be dark.
Reason: Red glass transmits only red light.

$A$ source emits light of wavelengths $4700 \ \mathring{A}$,$5400 \ \mathring{A}$,and $6500 \ \mathring{A}$. The light passes through red glass before being tested by a spectrometer. Which wavelength is seen in the spectrum?

The radius of the central zone of a circular zone plate is $2.3\,mm$. The wavelength of the incident light is $5893\,\mathring{A}$. The source is at a distance of $6\,m$. What is the distance of the first image in meters?