Electrostats

I guess you face problem of lack of knowledge of latex, please learn it as you can use it to make math elegant and to give complete solutions.Check for formatting guide . I am completing the solution below:

Here, we consider 3 more similar rectangles and cover them by horizontal lids to form a closed cuboid of dimensions $2a \times 2a \times 2h$ , See the figure below, here, the square is the part of cuboid cutting the disk.

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Now , the flux of electric field through all such upright cylinders would be equal , (say $\phi_{1}$ ), and through each one of horizontal lids $\phi_{2}$ would be $E_{\pm h} \times (2a)^2 = \frac{2 a^2 \sigma}{\epsilon_{0}} (1 - \frac{h}{\sqrt{h^2+R^2}})$ as (\ a << R)

By Gauss Law, total flux through the cuboid = $\frac{\sigma \times 4a^2}{\epsilon_{0}}$ .

Hence, $4 \phi_{1} + 2 \phi_{2} = \frac{\sigma \times 4a^2}{\epsilon_{0}}$

$\Rightarrow \boxed{\phi_{1} = \frac{\sigma \times a^2}{\epsilon_{0}} \frac{h}{\sqrt{h^2+R^2}}}$

do u call it a detailed solution........

jatin ...iam sorry..but i didnt understand..what have you done.....please help me out..i have problem in formula part