To make the central fringe at the centre $O,$ a mica sheet of refractive index $1.5$ is introduced. Choose the correct statements $\left(s\right)-$

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 $x$.