# Homework Help: What does flux of electric field physically signify?

1. Apr 12, 2006

### gandharva_23

What does flux of electric field physically signify ? What are we actually calculating by calculating flux . i read somewhere that it is the number of lines of electric lines passing normal to a given area . if we have a charge q then arent there infinite electric lines possible ?

2. Apr 12, 2006

### Physics Monkey

The flux of the electric field is essentially the amount of field going through a surface. It may help to think in terms of a fluid analogy where the flux does have the meaning of number of particles flowing across the surface in unit time. Note that this is only an analogy, however.

In electrical systems, the flux of the electric field through a surface is a measure of the charge enclosed by that surface. More charge inside produces a larger field and a greater flux.

This notion of counting of field lines is another helpful analogy, but as you have realized, the field line concept can be misleading. There are an infinite number of such lines since the field is defined everywhere in space.

Last edited: Apr 12, 2006
3. Apr 12, 2006

### robphy

The way to use field line diagrams is that the "density of field lines" is proportional to the strength of the field. The idea can be made more precise (and possibly more intuitive with sufficient motivation) using a different pictorial representation ("flux tubes") http://www.ee.byu.edu/forms/forms-home.html [Broken]

Last edited by a moderator: May 2, 2017