Thursday 4 April 2013

Flux of Electric Field


In general, flux is used to represent flow, like water flowing through a pipe. Here flux is used to represent the number of fields lines that cross through a surface.

Flux of electric field through an infinitesimally small surface is defined by the relation


Total flux through a given surface area is



Units: Sl unit of flux is N-m2/C or V-m (volt metre)

Consider the following three cases of uniform field. These are helpful in explaining, how flux can be calculated
It is to be noted that while calculating flux through an open surface  can be taken in any direction normal to the surface. But for closed surface, outward normal is the positive direction of area vector (d or ). Thus while calculating flux through a closed surface, outward flux is taken as positive and inwards flux is taken as negative.

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