The total number of electric lines of force that cut through a given surface area held perpendicular to the direction of electric lines of force is called electric flux.
It is represented by the Greek letter Ø . The surface through which the electric lines of force cross may be closed or open.
For closed surfaces electric flux is positive if the electric lines of force flow outwards and is negative if the electric lines of force flow inwards. Electric flux is positive for surface around charge +q and negative for surface around charge q2.
For an open surface electric lines of force of a uniform electric field (E) are closing a surface of area A perpendicular to the electric field. Therefore, Electric flux Ø, through the surface is given as
Ø = EA ......(1)
If the surface makes an angle θ with the direction of electric lines of force, then the electric flux is given as
Ø = EA cos θ
Units of Electric flux:
From the units of E and A the SI units of Electric flux are
N. m2 C−1 or JmC−1.
The number of lines of force coming out of a positively charged body determines the charge on the body in coulomb.
Therefore,units of electric flux are also expressed as coulomb. Thus if a positively charged body has a charge of q coulomb then, Electric flux due to charged body, Ø = q coulomb.
Electric flux through an area :
Electric flux through an area is defined as the number of electric lines of force passing through that area normally. It is a scalar quantity and is denoted by Ø.
dØ = E.dA ......(2)
where θ is the angle between E and dA.
If θ = 0°, i.e., E || dA, then flux is maximum and
To find flux through the whole closed surface A, we integrate eqn. (2) & (3) i.e.,
courtesy:vias.org
hyperphysics.phy -astr.gsu.edu
It is represented by the Greek letter Ø . The surface through which the electric lines of force cross may be closed or open.
For closed surfaces electric flux is positive if the electric lines of force flow outwards and is negative if the electric lines of force flow inwards. Electric flux is positive for surface around charge +q and negative for surface around charge q2.
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For an open surface electric lines of force of a uniform electric field (E) are closing a surface of area A perpendicular to the electric field. Therefore, Electric flux Ø, through the surface is given as
Ø = EA ......(1)
If the surface makes an angle θ with the direction of electric lines of force, then the electric flux is given as
Ø = EA cos θ
Units of Electric flux:
From the units of E and A the SI units of Electric flux are
N. m2 C−1 or JmC−1.
The number of lines of force coming out of a positively charged body determines the charge on the body in coulomb.
Therefore,units of electric flux are also expressed as coulomb. Thus if a positively charged body has a charge of q coulomb then, Electric flux due to charged body, Ø = q coulomb.
Electric flux through an area :
Electric flux through an area is defined as the number of electric lines of force passing through that area normally. It is a scalar quantity and is denoted by Ø.
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Let we have an area A in an electric field E, and let dA be small area vector element, then small flux (dØ) passing through small area (dA) is given by;
dØ = E.dA ......(2)
dØ = E dA cos θ .......(3)
where θ is the angle between E and dA.
If θ = 0°, i.e., E || dA, then flux is maximum and
when θ = 90°, i.e., E ⊥ dA, then flux is zero.
To find flux through the whole closed surface A, we integrate eqn. (2) & (3) i.e.,
Ø = ∮A E.dA
= ∮A E dA cos θ
Electric flux is a scalar quantity as it is dot product of two vector quantities E and dA.
hyperphysics.phy -astr.gsu.edu
Thank, my friend. It's a nice post about electric flux. I like the way you have described it. It's really helpful. But if you provide some examples or problems then it'll be a great post.
ReplyDeleteThe number of electric lines of force is called electric flux.
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the total number of electric lines of force passing certain area called electric flux. please complete information in comment.
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