Flow

Storyboard

If we observe the field lines, a type of flow can be associated in which the electric field plays the role of a type of velocity vector.

>Model

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Mechanisms

Iframe

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Code
Concept

Mechanisms

ID:(15787, 0)



Electric flow concept

Image

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Flow is defined by the electric field and the section that the field lines traverse:

ID:(11366, 0)



Electric field projection

Concept

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The dot product of two vectors $\vec{a}$ and $\vec{b}$ can be calculated using the magnitudes of the vectors and the angle $\theta$ between them, as follows:

$ \vec{a}\cdot\vec{b} = \mid\vec{a}\mid \mid\vec{b}\mid \cos \theta $



Since the versor normal to the section ($\hat{n}$) has a magnitude of one, the electric field projection ($E_n$) with the electric field ($\vec{E}$), the versor normal to the section ($\hat{n}$), and the surface normal electric field angle ($\alpha$) is:

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $

ID:(15789, 0)



Electric flow geometry

Concept

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The field is not necessarily orthogonal to the section through which the flux is being calculated. Therefore, it is necessary to calculate the component of the electric field that is orthogonal to the section:



Since the dot product of a vector with a unit vector, in this case, the unit vector that defines the orientation of the section, gives the projection of the vector onto this section, the component to consider is the dot product or the cosine of the angle the surface normal electric field angle ($\alpha$) between the electric field ($\vec{E}$) and the versor normal to the section ($\hat{n}$):

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $

ID:(11368, 0)



Flow by non-flat section and variable field

Concept

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As the section is not necessarily flat, the normal versor may vary its orientation. Similarly, the field can vary in direction and magnitude on the section. Therefore, the section can be segmented into small surface elements that can be considered flat at first approximation and in which the field does not vary either in direction or in magnitude:



Therefore, the electric flow ($\Phi$) is calculated by summing, over the entire section, the contribution of the normal component of the electric field to each element of the section, calculated from the surface electric field i ($\vec{E}_i$) and the versor normal to surface i ($\hat{n}_i$), and multiplied by the surface element i ($dS_i$):

$ \Phi \equiv \displaystyle\sum_i \vec{E}_i\cdot\hat{n}_i\,dS_i $



In the continuous limit, the sum can be replaced by the integral over the surface element ($dS$) of the dot product of the electric field ($\vec{E}$) and the versor normal to the section ($\hat{n}$):

$ \Phi = \displaystyle\int \vec{E} \cdot \hat{n} dS $

ID:(11373, 0)



The electric flow, depending on the angle

Concept

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The electric flow ($\Phi$) is defined as the normal component of the electric field, calculated from the surface electric field i ($\vec{E}_i$) and the versor normal to surface i ($\hat{n}_i$), multiplied by the surface element i ($dS_i$) for each element $i$, which is then summed over the entire section:

$ \Phi \equiv \displaystyle\sum_i \vec{E}_i\cdot\hat{n}_i\,dS_i $



On the other hand, the electric field projection ($E_n$) with the electric field ($\vec{E}$), the versor normal to the section ($\hat{n}$), and the surface normal electric field angle ($\alpha$) is equal to:

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $



Therefore, with the surface normal electric field angle i ($\alpha_i$) we have:

$ \Phi = \displaystyle\sum_i | \vec{E}_i | \cos\alpha_i dS $



This can be extended to the continuous case by replacing the sum with an integral over the surface element ($dS$) of the dot product of the electric field ($\vec{E}$) and the surface normal electric field angle ($\alpha$):

$ \Phi = \displaystyle\int | \vec{E} | \cos \alpha dS $

ID:(15790, 0)



Model

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Parameters

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$dS_i$
dS_i
Surface element i
m^2

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$E$
E
Electric eield
V/m
$E_n$
E_n
Electric field projection
N/C
$\Phi$
Phi
Electric flow
N m^2/C
$\vec{E}_i$
&E_i
Surface electric field i
V/m
$dS$
dS
Surface element
m^2
$\alpha$
alpha
Surface normal electric field angle
rad
$\alpha_i$
alpha_i
Surface normal electric field angle i
rad
$\hat{n}_i$
&n_i
Versor normal to surface i
-
$\hat{n}$
&&n
Versor normal to the section
-

Calculations


First, select the equation: to , then, select the variable: to

Calculations

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

Variable Given Calculate Target : Equation To be used




Equations

#
Equation

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $

&E * &n = @MOD( &E )*cos( alpha )


$ \Phi = \displaystyle\sum_i | \vec{E}_i | \cos\alpha_i dS $

Phi = dS_i *@MAG( &E_i )* cos( alpha_i )


$ \Phi = \displaystyle\int \vec{E} \cdot \hat{n} dS $

Phi = S * &n * &E


$ \Phi = \displaystyle\int | \vec{E} | \cos \alpha dS $

Phi = S * @MAG( &E ) * cos( alpha )


$ \Phi \equiv \displaystyle\sum_i \vec{E}_i\cdot\hat{n}_i\,dS_i $

Phi = sum(S_i * n_i * E_i,i)

ID:(15788, 0)



Electric field projection

Equation

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The electric field projection ($E_n$) is with the electric field ($\vec{E}$), the versor normal to the section ($\hat{n}$) and the surface normal electric field angle ($\alpha$) equal to:

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $

$E$
Electric eield
$V/m$
5464
$E_n$
Electric field projection
$V/m$
8552
$\alpha$
Surface normal electric field angle
$rad$
8549

The dot product of two vectors $\vec{a}$ and $\vec{b}$ can be calculated using the magnitudes of the vectors and the angle $\theta$ between them, as follows:

$ \vec{a}\cdot\vec{b} = \mid\vec{a}\mid \mid\vec{b}\mid \cos \theta $



Since the versor normal to the section ($\hat{n}$) has a magnitude of one, the electric field projection ($E_n$) with the electric field ($\vec{E}$), the versor normal to the section ($\hat{n}$), and the surface normal electric field angle ($\alpha$) is:

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $

ID:(11371, 0)



The electrical flow

Equation

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The electric flow ($\Phi$) is defined as the normal component of the electric field, calculated from the surface electric field i ($\vec{E}_i$) and the versor normal to surface i ($\hat{n}_i$), multiplied by the surface element i ($dS_i$) for each element $i$, which is then summed over the entire section:

$ \Phi \equiv \displaystyle\sum_i \vec{E}_i\cdot\hat{n}_i\,dS_i $

$\Phi$
Electric flow
$N m^2/C$
8542
$E_i$
Surface electric field i
$V/m$
8543
$dS_i$
Surface element i
$m^2$
8544
$\hat{n}_i$
Versor normal to surface i
$-$
8545

ID:(11372, 0)



The general electrical flow

Equation

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The electric flow ($\Phi$) is equal to the integral over the surface element ($dS$) of the dot product of the electric field ($\vec{E}$) and the versor normal to the section ($\hat{n}$):

$ \Phi = \displaystyle\int \vec{E} \cdot \hat{n} dS $

$E$
Electric eield
$V/m$
5464
$\Phi$
Electric flow
$N m^2/C$
8542
$dS$
Surface element
$m^2$
8547
$\hat{n}$
Versor normal to the section
$-$
8546

The electric flow ($\Phi$) is defined as the normal component of the electric field, calculated from the surface electric field i ($\vec{E}_i$) and the versor normal to surface i ($\hat{n}_i$), multiplied by the surface element i ($dS_i$) for each element $i$, which is then summed over the entire section:

$ \Phi \equiv \displaystyle\sum_i \vec{E}_i\cdot\hat{n}_i\,dS_i $



In the continuous limit, the sum can be replaced by the integral over the surface element ($dS$) of the dot product of the electric field ($\vec{E}$) and the versor normal to the section ($\hat{n}$):

$ \Phi = \displaystyle\int \vec{E} \cdot \hat{n} dS $

ID:(11367, 0)



The electric flow, depending on the angle

Equation

>Top, >Model


The electric flow ($\Phi$) is defined as the normal component of the electric field, calculated from the surface electric field i ($\vec{E}_i$) and the surface normal electric field angle i ($\alpha_i$), multiplied by the surface element i ($dS_i$) for each element $i$, which is then summed over the entire section:

$ \Phi = \displaystyle\sum_i | \vec{E}_i | \cos\alpha_i dS $

$\Phi$
Electric flow
$N m^2/C$
8542
$E_i$
Surface electric field i
$V/m$
8543
$dS_i$
Surface element i
$m^2$
8544
$\alpha_i$
Surface normal electric field angle i
$rad$
8548

The electric flow ($\Phi$) is defined as the normal component of the electric field, calculated from the surface electric field i ($\vec{E}_i$) and the versor normal to surface i ($\hat{n}_i$), multiplied by the surface element i ($dS_i$) for each element $i$, which is then summed over the entire section:

$ \Phi \equiv \displaystyle\sum_i \vec{E}_i\cdot\hat{n}_i\,dS_i $



On the other hand, the electric field projection ($E_n$) with the electric field ($\vec{E}$), the versor normal to the section ($\hat{n}$), and the surface normal electric field angle ($\alpha$) is equal to:

$ \vec{E} \cdot \hat{n} =\mid \vec{E} \mid\cos \alpha $



Therefore, with the surface normal electric field angle i ($\alpha_i$) we have:

$ \Phi = \displaystyle\sum_i | \vec{E}_i | \cos\alpha_i dS $

ID:(11370, 0)



The general electrical flow, as a function of the angle

Equation

>Top, >Model


The electric flow ($\Phi$) is equal to the integral over the surface element ($dS$) of the dot product of the electric field ($\vec{E}$) and the surface normal electric field angle ($\alpha$):

$ \Phi = \displaystyle\int | \vec{E} | \cos \alpha dS $

$E$
Electric eield
$V/m$
5464
$\Phi$
Electric flow
$N m^2/C$
8542
$dS$
Surface element
$m^2$
8547
$\alpha$
Surface normal electric field angle
$rad$
8549

The electric flow ($\Phi$) is defined as the normal component of the electric field, calculated from the surface electric field i ($\vec{E}_i$) and the surface normal electric field angle i ($\alpha_i$), multiplied by the surface element i ($dS_i$) for each element $i$, which is then summed over the entire section:

$ \Phi = \displaystyle\sum_i | \vec{E}_i | \cos\alpha_i dS $



This can be extended to the continuous case by replacing the sum with an integral over the surface element ($dS$) of the dot product of the electric field ($\vec{E}$) and the surface normal electric field angle ($\alpha$):

$ \Phi = \displaystyle\int | \vec{E} | \cos \alpha dS $

ID:(11369, 0)