Electic field / capacitance of parallel plates

In summary, when calculating the electric field for a plate of charge using the equation E = Q/Ae, where Q is the charge on the plate, A is the area of the plate, and e is the permittivity of the dielectric, it is important to note that the total electric field between the plates is actually twice the calculated value due to the equal but opposite charge on the other plate. This is often not mentioned in the equation, but can be visualized by making a Gauss pillbox around the capacitor. The equation E = Q/Ae is only for the charge on one plate and does not take into account the charge on the other plate.
  • #1
specone
5
0
Upon calculating the electric field for a plate of charge, you arrive at:

E = Q/Ae (Q the charge on the plate, A the area of the plate, e the permittivity of the dielectic)

But then, isn't the total electric field between the plates twice this because of the equal but opposite charge on the other plate?

I always see it written without a factor of 2.
 
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  • #2
which way is the E field going , make a Gauss pillbox around the capacitor .
 
  • #3
specone said:
Upon calculating the electric field for a plate of charge, you arrive at:

E = Q/Ae (Q the charge on the plate, A the area of the plate, e the permittivity of the dielectic)

But then, isn't the total electric field between the plates twice this because of the equal but opposite charge on the other plate?

I always see it written without a factor of 2.

Is that equation only for the charge on 1 plate, or for both plates? Looks to me like it is only for the 1 plate based on your post.
 

FAQ: Electic field / capacitance of parallel plates

What is an electric field?

An electric field is a region in which an electric charge experiences a force. It is created by a source charge and can be either attractive or repulsive.

How is an electric field created between parallel plates?

An electric field is created between parallel plates when a potential difference is applied between them. The positive plate becomes positively charged and the negative plate becomes negatively charged, creating an electric field between them.

What is the equation for the electric field between parallel plates?

The equation for the electric field between parallel plates is E = V/d, where E is the electric field strength, V is the potential difference between the plates, and d is the distance between the plates.

How does the distance between parallel plates affect the electric field strength?

The electric field strength between parallel plates is inversely proportional to the distance between the plates. This means that as the distance between the plates increases, the electric field strength decreases, and vice versa.

What is capacitance and how is it related to the electric field between parallel plates?

Capacitance is the ability of a system to store an electric charge. In the case of parallel plates, the capacitance is directly proportional to the electric field strength and the area of the plates, and inversely proportional to the distance between the plates. This means that as the electric field strength or plate area increases, the capacitance increases, and as the distance between the plates increases, the capacitance decreases.

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