In an arrangement to view the interference pattern produced by a wedge of liquid between a microscope slide and a glass block the interference pattern obtained is made of equally spaced parallel fringes. The fringe separation (or fringe width) can not be decreased by which of the following actions.

Consider interference between two sources of intensity $I$ and $4I$. Find out resultant intensity where phase difference is

$\frac{\pi }{4}$ 

Express all your answers in the form $nI$ where $n$ is real number up to two decimal places. Find $n$.

Consider interference between two sources of intensity $I$ and $4I$. Find out resultant intensity where phase difference is $\pi$

Express all your answers in the form $nI$ where $n$ is real number up to two decimal places. Find $n$.

Consider interference between two sources of intensity $I$ and $4I$. Find out resultant intensity where phase difference is $4\pi$

Express all your answers in the form $nI$ where $n$ is real number up to two decimal places. Find $n$.

A ray of light of intensity I is incident on a parallel glass-slab at a point $A$ as shown in figure. It undergoes partial reflection and refraction. At each reflection $20\%$ of incident energy is refracted. The rays $AB$ and $A^{\text{'}}{B}^{\text{'}}$ undergo interference. The ratio of $\frac{I_{\max }}{I_{\min }}$ is $x:1$. Write the value of $x$.

A thin glass plate of thickness $t$ and refractive index $\mu$ is inserted between screen and one of the slits in a Young's experiment. If the intensity at the centre of the screen is $I$, what was the intensity at the same point prior to the introduction of the sheet.
Express your answer as $I{\cos }^2\left[\frac{k(\mu -1)t}{\lambda }\right]$ and find the value of $k$.

(Take $\pi =3.14$)

Light of wavelength $520 \mathrm{nm}$ passing through a double slit, produces interference pattern of relative intensity versus deflection angle $\theta$ as shown in the figure. Find the separation $d$ between the slits. If your answer is $x\times {10}^{-2} \mathrm{mm}$, fill the value of $x$.