Question

Unit of electric flux is:

• A. $Vm$
• B. $Nm/C$
• C. $V/m$
• D. $C/Nm$

Answer 1

The correct option is A $Vm$

Electric flux in an electric field represents the total number of electric field lines crossing the area.
Electric flux over an area in an electric field represents the total number of electric field lines crossing this area. It is represented by ${\varphi }_E$ and is given by the product of surface area and the components of electric field intensity normal to the area.
If $\overrightarrow{E}$ is electric field intensity over a small area element $\overrightarrow{dS}$ and $\theta$ is angle between $\overrightarrow{E}$ and outdrawn normal to area element. Therefore, electric flux through this element is
${d\varphi }_E=\left(dS\right)\left(E\cos \theta \right)$
$=EdS\cos \theta =\overrightarrow{E}\cdot \overrightarrow{dS}$
Hence, ${\varphi }_E=E\cdot S$
$=\frac{V}{d}\cdot S$
$\therefore Unitof{\varphi }_E=\frac{volt\times {metre}^2}{metre}$
$=volt-metre$