What is the difference?flux and charge

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In summary: The difference between electric flux and charge is that electric flux is the flow of charge, while charge is the physical charge in an object. Electric flux is measured in coulombs per second, while charge is measured in coulombs.Both electric flux and charge have the same symbol, q, and the same units of coulombs. The only difference between them is that gauss's law uses flux density (D) instead of charge.Gauss's law is a law that describes the strength of an electric field. It uses the term flux density instead of charge because flux density is a more accurate measure of the electric field's strength. Gauss's law uses the
  • #1
i can't seem to wrap my head around flux theory.

what is the difference between electric flux and charge?
both have same units(coulombs) and symbol q or Q
but gauss' law uses flux density (D) and not charge

also if phi(F) is magnetic flux then what is component like 'charge' in magnetism?
 
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  • #2
I doubt anyone here will be able to explain it better than it has already been explained in numerous resources. Google the concepts, and if there is something particular regarding the concepts that is a bit hazy, then come back to clarify a minute detail.
 
  • #3
Electric Flux is the flow of charge through a certain area per time. It is a quantity that describes the electric field strength. The stronger an electric field, the more charge per unit area.
 
  • #4
Gauss was one heavy dude.
sometimes i resort to the ridiculous to get my thinking straight,,, reducto ad absurdum...

i think, as previous poster said, the equations do not make it intuitively obvious whether they are describing total flux or flux density. so try this simple thought then go back to your text and see if we missed some subtlety..,

imagine a closed gaussian surface surrounding a skunk.
if that gaussian surface has an area of just one square meter
there'll be an intense field of lepew emanating from it.
if one moves his gaussian surface further out, for the obvious reason, and repeats his closed surface integral, well, it'll be a more comfortable measurement to make even if more tedious.
If the new gaussian surface has an area of 1,000 sq meters the field strength there is attenuated a thousandfold. The same lepew is spread over a thousand times the area.
But the charge enclosed is the same - one skunk..

one skunk per sq meter is too intense, one per acre is tolerable.

i hope i did not mis-understand your question.
 
  • #5
jim hardy said:
If the new gaussian surface has an area of 1,000 sq meters the field strength there is attenuated a thousandfold. The same lepew is spread over a thousand times the area.
But the charge enclosed is the same - one skunk..

one skunk per sq meter is too intense, one per acre is tolerable.

i hope i did not mis-understand your question.

Another way to think of this (it turns out to be the same inverse square law) is gravity.
 
  • #6
indeed if E is volts/meter

think of point source and inverse square law
 
  • #7
If you think of electric field as radially spreading field lines(usual notation), the electric field is greater where field lines are denser, ergo electric field is in direct proportion of the density of the field lines(in a plane perpendicular to the field lines).

Integrating that density over the entire surface(that field lines are penetrating) gives the number of field lines penetrating the surface, and that is exactly what the expression for electric flux gives.

This is what flux represents. Good ANALOGY is flow of water. If you ask yourself, how many particles are flowing through some random chosen closed surface, you will get the flux through that surface.

But this is analogy, and this should only HELP you get your intuition, but do not consider ELECTRIC flux as flow of particles.
 
  • #8
[URL]http://courses.science.fau.edu/~rjordan/rev_notes/images/22.1.gif[/URL]

If you have a QuickTime player, this animation explains it very well:

"courses.science.fau.edu/~rjordan/rev_notes/movies/EFM06AN1.MOV"[/URL]

[QUOTE]This video clip was obtained from the "Core Concepts in Physics" CD-ROM produced by Saunders College Publishing. They are to be used for Educational Purposes only; do not copy.[/QUOTE]

[URL]http://courses.science.fau.edu/~rjordan/rev_notes/22.1.htm"[/URL]
 
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  • #9
Flux is the sum total of all the influences on your wallet while charge is the contents therein.
 
  • #10
study4years said:
i can't seem to wrap my head around flux theory.

what is the difference between electric flux and charge?
both have same units(coulombs) and symbol q or Q
but gauss' law uses flux density (D) and not charge

also if phi(F) is magnetic flux then what is component like 'charge' in magnetism?

Electric flux and charge are totally different. Electric charge is physical charge, electric flux is field lines generated by charges.

Electric charge unit is coulomb, Flux is more a force kind of thing that the unit is V/m. As in volt per meter. It is a force. Usually we talk about flux as field lines where you see pictures of curve lines from a +ve charge to a -ve charge.

In math point of view, Flux lines are vector fields where every point in space has it's own vector with amplitude and direction as a function.
 
  • #11
dacruick said:
Electric Flux is the flow of charge through a certain area per time. It is a quantity that describes the electric field strength. The stronger an electric field, the more charge per unit area.

Flux is not a flow of charges. Flux is generated by charges. It is a force field. Look at any book for Calculus III multi-variables under the topic of Vector Field and you'll see example of electric field and explanation of static electric field is a conservative field that is path independent.
 
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  • #12
Bassalisk said:
If you think of electric field as radially spreading field lines(usual notation), the electric field is greater where field lines are denser, ergo electric field is in direct proportion of the density of the field lines(in a plane perpendicular to the field lines).

Integrating that density over the entire surface(that field lines are penetrating) gives the number of field lines penetrating the surface, and that is exactly what the expression for electric flux gives.

This is what flux represents. Good ANALOGY is flow of water. If you ask yourself, how many particles are flowing through some random chosen closed surface, you will get the flux through that surface.

But this is analogy, and this should only HELP you get your intuition, but do not consider ELECTRIC flux as flow of particles.

What you are referring to is only a specific condition where there is only a point charge and the fields are radial fields that generated at the point of charge and radiate out evenly in all direction and the intensity diminish as inverse square of distance from the point.

In real life, we can have distribution of charges, moving charges and they form complicated shape. that is where vector fields come into play. From the distribution of charges, you find the sum of the fields of all charges at any point and get the resultant vector field of that point.

For point charge:

[tex]\vec E =\frac {q\hat r}{4\pi \epsilon_0 r^2}\;\hbox {where }\; \hat r \;\hbox { is the radial vector from the center to the point and }\; r\;\hbox { is the distance from the center.}[/tex]

For a distribution of n charges:

[tex] \vec E = \sum_{i=1}^n \frac {q\hat r_i}{4\pi \epsilon_0 r_i^2}\;\hbox { where }\;\hat r_i \;\hbox { is the vector from the i^th charge to the point.}[/tex]
 
  • #13
jim hardy said:
imagine a closed gaussian surface surrounding a skunk.
if that gaussian surface has an area of just one square meter
there'll be an intense field of lepew emanating from it.

if one moves his gaussian surface further out, for the obvious reason, and repeats his closed surface integral, well, it'll be a more comfortable measurement to make even if more tedious.
If the new gaussian surface has an area of 1,000 sq meters the field strength there is attenuated a thousandfold. The same lepew is spread over a thousand times the area.
But the charge enclosed is the same - one skunk..

one skunk per sq meter is too intense, one per acre is tolerable.

thanks the skunk theory helped...also thank you for the video...
 

What is flux?

Flux is the measure of how much of a given quantity, such as electric field or magnetic field, passes through a given area. It is represented by the symbol Φ (phi) and its unit is the weber (Wb).

What is charge?

Charge is a fundamental property of matter that causes it to experience electromagnetic interactions. It is represented by the symbol Q and its unit is the coulomb (C).

What is the difference between flux and charge?

The main difference between flux and charge is that flux is a measure of the flow of a quantity through a given area, while charge is a fundamental property of matter. Flux can be positive or negative, while charge can only be positive or negative depending on the type of charge.

How are flux and charge related?

Flux and charge are related through the equation Φ = Q / ε, where Φ is flux, Q is charge, and ε is the permittivity of the medium through which the flux is passing. This equation shows that the amount of flux is directly proportional to the amount of charge.

Why is understanding the difference between flux and charge important?

Understanding the difference between flux and charge is important because these two concepts are fundamental to understanding electromagnetism and many other areas of physics. Without a clear understanding of flux and charge, it is difficult to comprehend how electricity and magnetism work and how they interact with matter.

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