# Dielectric Help: Solving Parallel Plate Capacitor

• Bob Loblaw
In summary, the conversation was about solving a problem involving creating a parallel plate capacitor with different dielectric materials. The largest and smallest possible capacitance values were found using the given information and the capacitance equation. In the end, the mistake of using the wrong area measurement was discovered as the reason for incorrect values.
Bob Loblaw
[SOLVED]Dielectric help

## Homework Statement

To make a parallel plate capacitor, you have available two flat plates of aluminum (area = 180 cm2), a sheet of paper (thickness = 0.10 mm, k= 3.5), a sheet of glass (thickness = 2.0 mm, . k= 7.0), and a slab of paraffin (thickness = 10.0 mm, k= 2.0).
(a) What is the largest capacitance possible using one of these dielectrics?
_________nF
(b) What is the smallest?
________pF

## Homework Equations

$$C=k\epsilon_0 \frac{A}{d}$$

## The Attempt at a Solution

I used the above equation to evaluate the capacitance of each in this manner:
1) 3.5*8.85e-12*.180m^2/.0001 = 5.5755e-8
2) 7.0*8.85e-12*.180m^2/.002 = 5.5755e-9
3) 2.0*8.85e-12*.180m^2/.010 = 3.186e-10

I recorded the largest as .55.755 and the smallest as 318.6 (in their appropriate units) both of which were wrong. Any ideas where I messed up?

Last edited:
self-solved it. 180cm2 is .018m2, not .180m2 as I have recorded.

Thank you for sharing your solution attempt. It seems like you have correctly applied the formula for capacitance using the given dielectrics and dimensions. However, it is important to note that the units for capacitance are Farads, not nF or pF. Therefore, your answers should be in the form of 55.755 nF and 318.6 pF respectively. Also, make sure to double check your calculations to ensure accuracy. Keep up the good work!

## 1. What is a parallel plate capacitor?

A parallel plate capacitor is a device that stores electrical energy by creating an electric field between two parallel conductive plates separated by a dielectric material. It consists of two parallel metal plates, typically made of metal, that are connected to a power source.

## 2. How does a parallel plate capacitor work?

A parallel plate capacitor works by storing electrical energy in the form of an electric field between its two plates. When a voltage is applied to the plates, an electric field is created between them, causing opposite charges to accumulate on each plate. The dielectric material between the plates helps to maintain this electric field, allowing the capacitor to store energy.

## 3. What is the role of dielectric material in a parallel plate capacitor?

The dielectric material in a parallel plate capacitor serves as an insulator between the two plates, preventing them from coming into direct contact with each other. This allows the capacitor to store more charge and have a larger capacitance, as the dielectric reduces the electric field between the plates, making it easier to maintain a higher potential difference.

## 4. How do you calculate the capacitance of a parallel plate capacitor?

The capacitance of a parallel plate capacitor can be calculated using the formula C = ε₀A/d, where C is the capacitance, ε₀ is the permittivity of free space, A is the area of the plates, and d is the distance between the plates. This formula assumes a vacuum between the plates, but can be adjusted for different dielectric materials by using the permittivity of the material in place of ε₀.

## 5. What factors affect the capacitance of a parallel plate capacitor?

The capacitance of a parallel plate capacitor is affected by several factors, including the area of the plates, the distance between the plates, and the dielectric material used. Increasing the area of the plates or decreasing the distance between them will increase the capacitance, while using a material with a higher permittivity will also increase the capacitance.

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