Capacitors and dielectrics

In summary, the conversation discusses building a parallel plate capacitor with two square metal plates, a thin piece of dielectric, and the equations needed to calculate its capacitance and charge capacity. The equations include eq1 for calculating capacitance with no dielectric, eq2 for calculating capacitance with a dielectric, eq3 for calculating charge using capacitance and voltage, and eq4 for calculating voltage with electric field and distance. The final part of the conversation involves applying these equations with specific values to find the capacitance and charge capacity of a capacitor made with paper as the dielectric.
  • #1
vysero
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0

Homework Statement



You are building a parallel plate capacitor out of two square metal plates with side lengths of L and a thin piece of dielectric of thickness d and dielectric strength of Eb. The piece of dielectric will act as a means of separating the two metal plates. In terms of l, Eo(epsilon knot), k, d, Eb how much charge can the capacitor hold before it fails? With l = 10cm, d = .1mm and paper as a dielectric what is the capacitance of your capacitor? How much charge can the capacitor hold before it fails?[/B]

Homework Equations



eq1: C = EoL; L for a parallel-plate capacitor is = A/d

with a dielectric completely filling the space between the plates:[/B]

eq 2: C = kEo(A/d)
eq 3: q = CV
eq 4: V = E/d


The Attempt at a Solution



Using those equations I came up with:

q = CV = (kEoL^2/d)(Eb/d) = EbkL^2Eo/d^2

For the second part of the question with k = 3.5 and eq2 I come up with:

C = 3.5(8.85x10^(-12))(.1^2/.0001) = 3.096 x 10^-9 F

and for the final equation where Eb = 16 I said:

q = 16(3.5)(.1)^2(8.85x10^(-12))/(.0001)^2
= 4.96x10^(-4) C

However, I made the assumption that E = Eb in eq3. If someone could check my work and tell me if I did this problem correctly that would be great, any help appreciated.[/B]
 
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  • #2
vysero said:

Homework Statement



You are building a parallel plate capacitor out of two square metal plates with side lengths of L and a thin piece of dielectric of thickness d and dielectric strength of Eb. The piece of dielectric will act as a means of separating the two metal plates. In terms of l, Eo(epsilon knot), k, d, Eb how much charge can the capacitor hold before it fails? With l = 10cm, d = .1mm and paper as a dielectric what is the capacitance of your capacitor? How much charge can the capacitor hold before it fails?[/B]

Homework Equations



eq1: C = EoL; L for a parallel-plate capacitor is = A/d

with a dielectric completely filling the space between the plates:[/B]

eq 2: C = kEo(A/d)
eq 3: q = CV
eq 4: V = E/d


I do not understand what you mean with eq 1, and the last equation (eq 4) is wrong . Check.
 

1. What is a capacitor?

A capacitor is an electronic component that stores and releases electrical energy in the form of an electric charge. It is made up of two conductive plates separated by an insulating material, called a dielectric.

2. How does a capacitor work?

When a capacitor is connected to a power source, one plate accumulates a positive charge and the other accumulates a negative charge. The dielectric material between the plates prevents the charges from flowing together, creating an electric field. This electric field stores the energy in the form of potential energy. When the capacitor is disconnected from the power source, the stored energy can be released as a current.

3. What is the purpose of a dielectric in a capacitor?

The dielectric in a capacitor serves as an insulating material between the two plates. It prevents the flow of electric current between the plates, allowing the capacitor to store energy. The type of dielectric used can also affect the capacitance and other properties of the capacitor.

4. How are capacitors and dielectrics used in electronic circuits?

Capacitors and dielectrics are used in electronic circuits for a variety of purposes. They can be used to filter out unwanted frequencies, store energy, stabilize voltage levels, and block direct current. They are also commonly used in timing circuits and as a component in power supplies.

5. What are some common types of dielectrics used in capacitors?

There are many different types of dielectrics used in capacitors, including air, paper, ceramic, plastic, and electrolytic materials. Each type of dielectric has its own unique properties and is suited for different applications. For example, ceramic capacitors are often used in high-frequency circuits, while electrolytic capacitors are commonly used in power supply applications.

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