Finding electric field through capacitor

In summary, a parallel-plate capacitor with two dielectrics (A and B) is placed in a circuit with 10V applied. Dielectric A has 0.001m width and relative permittivity 2, while dielectric B has 0.003m width and relative permittivity 4. The plates have an area of 0.01m^2. The electric field through each dielectric can be calculated using the formula E = V/d, where V is the voltage and d is the distance between the plates. The electric field for dielectric A is 4000 V/m, while the electric field for dielectric B is 2000 V/m. The electric displacement field D is also important
  • #1
geft
148
0
A parallel-plate capacitor with two dielectrics is placed in a circuit with 10V applied.

Dielectric A has 0.001m width and relative permittivity 2. Dielectric B has 0.003m width and relative permittivity 4. The plates have area of 0.01m^2. What is the electric field through each dielectric? (Ans: 4000 V/m and 2000 V/m)

I know the formula used is E = V/d, but how do I divide the voltage between these dielectrics?
 
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  • #2
hi geft! :smile:
geft said:
I know the formula used is E = V/d, but how do I divide the voltage between these dielectrics?

why would the width matter?

start with the electric displacement field D …

what is its magnitude, and how is E related to it? :wink:
 
  • #3
D = eE

E = D/e = V/d

...but I wouldn't be able to get the displacement field without the electric field, right?
 
  • #4
displacement field was invented for the capacitor …

D = -Q/A :wink:​
 
  • #5
Didn't know that formula, thanks! :)
 
  • #6
oooh, i forgot to mention …

that's exactly why the electric displacement field D is measured in units of coulombs per square metre, C/m2 :biggrin:​
 

1. What is an electric field?

An electric field is a physical quantity that describes the influence of electric charges on each other. It is a vector quantity, meaning it has both magnitude and direction, and is measured in units of volts per meter (V/m).

2. How is electric field related to capacitors?

Capacitors are devices that store electric charge and are made up of two conducting plates separated by an insulating material. The electric field is responsible for the buildup of charge on the plates of a capacitor, and the strength of the field is directly proportional to the amount of charge stored on the plates.

3. How do you find the electric field between the plates of a capacitor?

The electric field between the plates of a capacitor can be found by dividing the voltage (V) across the plates by the distance (d) between them. This can be expressed as E = V/d, where E is the electric field in V/m.

4. What factors affect the strength of the electric field in a capacitor?

The strength of the electric field in a capacitor is affected by the distance between the plates, the magnitude of the charge on the plates, and the type of material between the plates (known as the dielectric). As the distance between the plates decreases or the charge on the plates increases, the electric field becomes stronger. The type of dielectric can also affect the electric field strength.

5. Can the electric field through a capacitor be changed?

Yes, the electric field through a capacitor can be changed by adjusting the distance between the plates, changing the amount of charge on the plates, or changing the type of dielectric between the plates. Additionally, the direction of the electric field can be changed by reversing the polarity of the voltage source connected to the capacitor.

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