Electric Field and Gaussian Pillbox

In summary, the conversation discusses checking the consistency of a problem's result with a given statement. It involves finding the electric field of an infinite plane with a uniform surface charge, using a Gaussian Pillbox and symmetry to determine the direction and magnitude of the electric field. The result of \vec{E_{above}} - \vec{E_{below}} = \frac{\sigma}{\epsilon_{0}} \hat{n} is consistent with the statement and can be considered a satisfactory proof.
  • #1
stunner5000pt
1,465
4
check whether this result of this problem is consistent with this statement
[tex] \vec{E_{above}} - \vec{E_{below}} = \frac{\sigma}{\epsilon_{0}} \hat{n} [/tex]


an infinite plan carries a uniform surface charge sigma. Find its electric field
Solution:

Draw a Gaussian Pillbox extending above and below the plane. Then
since [tex] \oint \vec{E} \bullet d\vec{a} = \frac{Q_{enc}}{\epsilon_{0}} [/tex]

and since[tex]Q_{enc} = \sigma A [/tex]

By Symmetry E points up and down

so
[tex] \int \vec{E} \bullet d\vec{a} = 2A |\vec{E}| [/tex]

so [tex] \vec{E} = \frac{\sigma}{2\epsilon_{0}} \hat{n} [/tex]

Now to tackle the question

Well for an infinite sheet for each side the Electric field points normal to the sheet, right?
SO the electric field for the top is [itex] \vec{E} = \frac{\sigma}{\epsilon_{0}} \hat{n} [/itex]
and te bottom is the negative of that

So when you add those two together you get [tex] \vec{E} = \frac{\sigma}{\epsilon_{0}} \hat{n}[/tex]

and this is consistent with statement. Easy enough. i just want to know whether this kind of 'proof' for the statement is satisfactory.
 
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  • #2
yeah that's right.
 

FAQ: Electric Field and Gaussian Pillbox

What is an electric field?

An electric field is a physical field that describes the influence that electrically charged objects have on each other. It is a vector field, meaning that it has both magnitude and direction, and is created by the presence of electric charges.

How is an electric field measured?

An electric field is measured in units of volts per meter (V/m) or newtons per coulomb (N/C). The strength of an electric field can be measured using a device called an electric field meter.

What is a Gaussian pillbox?

A Gaussian pillbox is a conceptual device used in physics to simplify calculations involving electric fields. It is a hypothetical shape that is used to calculate the electric field at a point outside of a charged object, by assuming that the charge is concentrated within the pillbox.

How is the electric field calculated using a Gaussian pillbox?

The electric field at a point outside of a charged object can be calculated using the equation E = Q/(4πε0r2), where E is the electric field, Q is the charge enclosed within the pillbox, ε0 is the permittivity of free space, and r is the distance from the charge to the point where the electric field is being measured.

What is the relationship between electric field and electric potential?

Electric potential is a measure of the potential energy per unit charge at a given point in an electric field. The electric field is the negative gradient of the electric potential, meaning that the electric field points in the direction of decreasing potential. In other words, the electric field is the force per unit charge that a positive test charge would experience at a given point in the electric potential field.

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