Question: Q. 2. Define the term ’electric flux’. Write its S.I. unit.
R [Delhi Comptt. I, II, III 2013]
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Solution:
Ans. Electric flux through an area is the product of magnitude of area and the component of electric field vector normal to it.
$$ \begin{aligned} \phi & =\Delta S(E \cos \theta) \ \phi & =\vec{E} \cdot \Delta \vec{S} \end{aligned} $$
Or, Electric flux is defined as the total number of electric field lines passing through an area normal to it.
Or, Electric flux is the property of an electric field which may be thought of as number of electric lines of force which intersectsat given area.
The S.I. unit of ’electric flux’ is $\mathrm{NC}^{-1} \mathrm{~m}^{2}$.
[CBSE Marking Scheme, 2013]
