Question

The electric field in a region is given by
$E=(2\hat{i}+3\hat{j})\times {10}^{3}N{C}^{-1}$
The electric flux through a rectangular surface $10cm\times 20cm$ held parallel to the y-z plance is

• A. $40N{C}^{-1}{m}^2$
• B. $50N{C}^{-1}{m}^2$
• C. $60N{C}^{-1}{m}^2$
• D. zero

Answer 1

The correct option is A

$40N{C}^{-1}{m}^2$

$E_x=2\times {10}^{3}N{C}^{-1}$ and $E_y=3\times {10}^{3}N{C}^{-1}$
$S=10cm\times 20cm=200c{m}^2=2\times {10}^{-2}{m}^2$
The normal to the y-z plane is along the x-axis. Hence Flux $=E_{x}S=2\times {10}^3\times 2\times {10}^{-2}=40N{C}^{-1}{m}^2$
Hence the correct choice is (a)