|Updated On : 2017-02-19 at : 12:00:00|
What is the Meaning of Electric Flux - How is it defined ?
Electric Flux - Definition :
Electric flux gives the measure of flow of the electric field through a given area. We may define electric flux as-
“ Electric flux is proportional to the number of electric field lines passing normally through a surface.”
If the electric field is uniform, the electric flux passing through a surface of vector area S is calculated by following formula -
ΦE = E.S= E S cosθ
where - E is the electric field (measured in units of V ⁄ m), E is its magnitude, S is the area of the surface, and θ is the angle between the electric field lines and the normal (perpendicular) to S.
Now if we are dealing with a non-uniform electric field, then electric flux dΦE through an infinitesimaly small surface area dS is calculated by following formula-
dΦE = E.dS
The scalar product of electric field and area vector (Oh! off course area is not a vector, however in some case treating it as vector simplifies our situation without affecting the result). The total electric flux over a surface S is therefore given by the surface integral -
ΦE = ∫∫S E . dS
where E is the electric field and dS is a differential element of the surface S, with an outward facing surface normal defining its direction.
Now for a closed surface, electric flux is given by -
Unit of Electric Flux
Its dimensional formula is [ L3MT-3I-1 ].