Question

A cylinder of length $L$ and radius $b$ has its axis coincident with the x-axis. The electric field in this region is $\overrightarrow{E}=200\hat{i}$. Find the flux through the left end of cylinder.

• A. $0$
• B. $200\pi b^2$
• C. $100\pi b^2$
• D. $-200\pi b^2$

Answer 1

The correct option is D $-200\pi b^2$

$\overrightarrow{E}=200\hat{i}$
Area vector for the left end is $\overrightarrow{A}=-A\hat{i}$
$\varphi =\overrightarrow{E}.\overrightarrow{A}=-EA=-E\pi b^2=-200\pi b^2$