Examples of electric fields

Storyboard

Depending on the geometry of the distribution of charges, different electric fields are obtained.

>Model

ID:(1564, 0)



Conductor sphere with charge

Definition

In a conducting sphere with charges, these are distributed on the surface and with it the field inside is null. Outside it behaves like a point charge that is in the center of the sphere:

ID:(11451, 0)



Loaded infinite wire or cylinder, in vacuum

Image

In a conductor wire or cylinder with charges, these are distributed throughout the object, behaving like a long chain of point loads aligned on the axis:

ID:(11452, 0)



Surface of a cylinder

Note

The surface of a cylinder of radius r and height h is calculated according to:

ID:(10464, 0)



Insulating sphere with homogeneous charge

Quote

An insulating sphere in which charges have been homogeneously distributed, which cannot be moved because it is an insulating material, has an electric field that grows linearly inside and decreases with the inverse of the radius squared:

ID:(11450, 0)



Infinite conductor plane with load

Exercise

In a conducting plane, a Gaussian surface can be defined as a cylinder. Since the lateral walls are orthogonal to the electric field, they do not contribute to the net flux. Therefore, the only parts that contribute are the cylinder's end caps, which are surfaces parallel to the plane:

ID:(11453, 0)



Two plates with opposite charges

Equation

In the case of two plates with opposite charges there is a field of greater intensity between them. However, there is a minor field that can be described with field lines that emerge from one of the plates and return by giving an external turn to the opposite plate:

ID:(11454, 0)



Simple model for two plates with opposite charges

Script

To be able to calculate the field between the two plates in a simple way, it can be assumed that the external field is compensated and that most of it is only between the plates:

ID:(11455, 0)



Examples of electric fields

Storyboard

Depending on the geometry of the distribution of charges, different electric fields are obtained.

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$r$
r
Axle distance
m
$Q$
Q
Charge
C
$\sigma$
sigma
Charge density by area
C/m^2
$L$
L
Conductor length
m
$\epsilon$
epsilon
Dielectric constant
-
$r$
r
Disc radius
m
$r$
r
Distance between charges
m
$E$
E
Electric eield
V/m
$E_1$
E_1
Electric field in surface 1
N/C
$E_2$
E_2
Electric field in surface 2
N/C
$E_3$
E_3
Electric field in surface 3
N/C
$E_p$
E_p
Electric field of a point charge
V/m
$E_s$
E_s
Electric field of an infinite plate
V/m
$E_w$
E_w
Electric field of an infinite wire
V/m
$E_f$
E_f
Electric field, conducting sphere
V/m
$E_c$
E_c
Electric field, infinite conducting cylinder
V/m
$E_i$
E_i
Electric field, sphere, interior
V/m
$E_e$
E_e
Electric field, sphere, outer
V/m
$E_d$
E_d
Electric field, two infinite plates
V/m
$q$
q
Encapsulated charge on Gauss surface
C
$\lambda$
lambda
Linear charge density
C/m
$z$
z
Position on the z axis
m
$R$
R
Sphere radius
m
$S_1$
S_1
Surface 1
m^2
$S_2$
S_2
Surface 2
m^2
$S_3$
S_3
Surface 3
m^2
$S$
S
Surface of a sphere
m^2
$S$
S
Surface of the conductor
m^2

Calculations


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

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used



Equations

In the case of a spherical Gaussian surface, the electric field ($\vec{E}$) is constant in the direction of the versor normal to the section ($\hat{n}$). Therefore, using the charge ($Q$), the electric field constant ($\epsilon_0$), and the dielectric constant ($\epsilon$), it can be calculated by integrating over the surface where the electric field is constant ($dS$):

equation=3213

with the surface ($S$) for a sphere of radius a distance between charges ($r$):

equation=4731

Thus, the electric field of a point charge ($E_p$) results in:

equation

In the case of a spherical Gaussian surface, the electric field ($\vec{E}$) is constant in the direction of the versor normal to the section ($\hat{n}$). Therefore, using the charge ($Q$), the electric field constant ($\epsilon_0$), and the dielectric constant ($\epsilon$), it can be calculated by integrating over the surface where the electric field is constant ($dS$):

equation=3213

With the surface ($S$) for a cylinder of the axle distance ($r$) and the conductor length ($L$):

equation=10464

and the linear charge density ($\lambda$) calculated with the charge ($Q$):

equation=11459

Thus,

equation

In the case of a cylindrical Gaussian surface, the electric field ($\vec{E}$) is constant in the direction of the versor normal to the section ($\hat{n}$). Therefore, using the variables the charge ($Q$), the electric field constant ($\epsilon_0$), and the dielectric constant ($\epsilon$), the integral over the surface where the electric field is constant ($dS$) can be calculated through the following equation:

equation=3213

For a cylinder characterized by the axle distance ($r$) and the conductor length ($L$), the following applies:

equation=10464

Furthermore, the linear charge density ($\lambda$) is calculated using the charge ($Q$) according to the equation:

equation=11459

Thus, it is established that the electric field, infinite conducting cylinder ($E_c$) is:

equation

In the case of a spherical Gaussian surface, the electric field is constant, so the electric eield ($E$) can be calculated using the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), and the surface of the conductor ($S$), resulting in:

equation=11456

Given that the surface of a sphere ($S$) is equal to the pi ($\pi$) and the disc radius ($r$), we obtain:

equation=4731

Finally, the electric field, sphere, outer ($E_e$) together with the distance between charges ($r$) is equal to:

equation

Considering a spherical Gaussian surface, the electric field is constant. Therefore, the electric eield ($E$) is equal to the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), and the surface of the conductor ($S$) as shown by:

equation=11456

Since the surface area of the surface of a sphere ($S$) is equal to the pi ($\pi$) and the disc radius ($r$), we have:

equation=4731

The charge enclosed by the Gaussian surface, with the encapsulated charge on Gauss surface ($q$), the sphere radius ($R$), and the distance between charges ($r$), is given by:

equation=11461

Therefore, the electric field, sphere, interior ($E_i$) results in:

equation

According to Gauss's Law, the variables the surface where the electric field is constant ($dS$), the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), the versor normal to the section ($\hat{n}$), and the electric field ($\vec{E}$) satisfy the following equation:

equation=3213

In the case of a flat Gaussian surface, the field must be constant, so the relationship of the electric eield ($E$) with the surface of the conductor ($S$) is established as:

equation=11456

Since the charge density by area ($\sigma$) is equally defined by:

equation=11460

For the electric field of an infinite plate ($E_s$), the resulting expression is:

equation

In the case of a Gaussian surface for a plane, the electric field ($\vec{E}$) is constant in the direction of the versor normal to the section ($\hat{n}$). Therefore, using the variables the charge ($Q$), the electric field constant ($\epsilon_0$), and the dielectric constant ($\epsilon$), it can be calculated by integrating over the surface where the electric field is constant ($dS$):

equation=3213

Additionally, the charge density by area ($\sigma$) is calculated using the surface ($S$) and the charge ($Q$) according to the following equation:

equation=11460

Therefore, it follows that the electric field, two infinite plates ($E_d$) is:

equation

According to Gauss's Law, the variables the surface where the electric field is constant ($dS$), the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), the versor normal to the section ($\hat{n}$), and the electric field ($\vec{E}$) satisfy the following equation:

equation=3213

the electric eield ($E$) is with and the surface of the conductor ($S$) turns out

equation


Examples

The electric eield ($E$) is with the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$) and the surface of the conductor ($S$) is equal to:

kyon

With Gauss's law

equation=3213

for the case that the field is normal and constant on two surface we have

equation

With Gauss's law

equation=3213

for the case that the field is normal and constant on three surface we have

equation

In a conducting sphere with charges, these are distributed on the surface and with it the field inside is null. Outside it behaves like a point charge that is in the center of the sphere:

image

La superficie de una esfera es con list igual a

equation

The electric field of a point charge ($E_p$) is a function of the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), and the distance between charges ($r$) and is calculated as follows:

kyon

Para el caso de una superficie gausseana esf rica el campo es constante por lo que se puede calcular con list=11456 mediante

equation=11456



con la superficie de una esfera con list=4731

equation=4731



A una distancia r de una esfera de carga Q de radio R es igual con list a:

equation

In a conductor wire or cylinder with charges, these are distributed throughout the object, behaving like a long chain of point loads aligned on the axis:

image

The surface of a cylinder of radius r and height h is calculated according to:

principle

The linear charge density ($\lambda$) is calculated as the charge ($Q$) divided by the conductor length ($L$):

kyon

The electric field of an infinite wire ($E_w$) is a function of the linear charge density ($\lambda$), the axle distance ($r$), the dielectric constant ($\epsilon$) and the electric field constant ($\epsilon_0$) and is calculated through:

kyon

The electric field, infinite conducting cylinder ($E_c$) is with the pi ($\pi$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), the linear charge density ($\lambda$) and the axle distance ($r$) is equal to:

kyon

An insulating sphere in which charges have been homogeneously distributed, which cannot be moved because it is an insulating material, has an electric field that grows linearly inside and decreases with the inverse of the radius squared:

image

The electric field, sphere, outer ($E_e$) is with the pi ($\pi$), the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$) and the distance between charges ($r$) is equal to:

kyon

In the case of a the sphere radius ($R$) sphere with homogeneous charge, the Gaussian surface for the distance between charges ($r$) includes the encapsulated charge on Gauss surface ($q$) for the charge ($Q$) :

kyon

The electric field, sphere, interior ($E_i$) is with the pi ($\pi$), the charge ($Q$), the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$), the sphere radius ($R$) and the distance between charges ($r$) is equal to:

kyon

In a conducting plane, a Gaussian surface can be defined as a cylinder. Since the lateral walls are orthogonal to the electric field, they do not contribute to the net flux. Therefore, the only parts that contribute are the cylinder's end caps, which are surfaces parallel to the plane:

image

The surface charge density is calculated by dividing the total charge by the surface area. Therefore, the relationship between the charge density by area ($\sigma$) and the charge ($Q$) with the surface of the conductor ($S$) is established as:

kyon

The electric field of an infinite plate ($E_s$) is with the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$) and the charge density by area ($\sigma$) equal to:

kyon

In the case of two plates with opposite charges there is a field of greater intensity between them. However, there is a minor field that can be described with field lines that emerge from one of the plates and return by giving an external turn to the opposite plate:

image

To be able to calculate the field between the two plates in a simple way, it can be assumed that the external field is compensated and that most of it is only between the plates:

image

The electric field, two infinite plates ($E_d$) is with the electric field constant ($\epsilon_0$), the dielectric constant ($\epsilon$) and the charge density by area ($\sigma$) is equal to:

kyon


>Model

ID:(1564, 0)