Energy density of a capacitor

In summary: Using the value of 'A' calculated previously, find the energy density.In summary, to find the energy density of a parallel-plate capacitor with a vacuum between plates, you must first find the area of the plates using the formula C= ε0A/d. Then, using the calculated area and given separation between plates, you can find the energy density by dividing the stored energy by the volume between the plates.
  • #1
baker265
12
0

Homework Statement



A parallel-plate capacitor with C = 16 mu or micro FF is charged so as to contain 1.7 J of energy. If the capacitor has a vacuum between plates that are spaced by 0.35 mm, what is the energy density (the energy per unit volume)?

I am a little lost of this problem and have no idea if I'm doing it correctly. Am I ?

Homework Equations


v = A*d
E,density=U/v


The Attempt at a Solution


v=16e-3/.35e-3=45.71
E=1.7/45.71=.0371 J/m^3
 
Physics news on Phys.org
  • #2
baker265 said:

Homework Statement



A parallel-plate capacitor with C = 16 mu or micro FF is charged so as to contain 1.7 J of energy. If the capacitor has a vacuum between plates that are spaced by 0.35 mm, what is the energy density (the energy per unit volume)?

I am a little lost of this problem and have no idea if I'm doing it correctly. Am I ?

Homework Equations


v = A*d
E,density=U/v


The Attempt at a Solution


v=16e-3/.35e-3=45.71 ?
E=1.7/45.71=.0371 J/m^3

Is the capacitance 16 μF (microfarad)?

How do you calculate the volume?

ehild
 
  • #3
Yes, I believe that is (microfarad); it doesn't say specifically.
I was very unsure on that step and wasn't quite sure how to compute the volume. Do I even to find the volume?
 
  • #4
As yo have written, energy density is energy divided by volume. So you need it.

ehild
 
  • #5
Okay so how do I find the area in order to find volume.
 
  • #6
What is the formula for the capacitance? ehild
 
  • #7
C=(k* epsilon_0*A)/d
 
  • #8
The volume between the plates is given by Ad where 'A' is area of the plates and 'd' is separation between them . 'd' is given whereas 'A' is unknown .

Using C= ε0A/d ,find the value of A.

Now,energy density = Energy stored/volume .
 

1. What is energy density of a capacitor?

The energy density of a capacitor refers to the amount of energy that can be stored in the capacitor per unit volume or unit mass. It is measured in joules per cubic meter (J/m3) or joules per kilogram (J/kg).

2. How is energy density of a capacitor calculated?

The energy density of a capacitor can be calculated by multiplying the capacitance (in farads) by the square of the voltage (in volts) and dividing by 2. This can be represented by the formula E = 1/2 * C * V^2.

3. What factors affect the energy density of a capacitor?

The energy density of a capacitor is affected by several factors, including the type of dielectric material used, the distance between the plates, and the voltage applied. Generally, a higher dielectric constant, thinner distance between plates, and higher voltage can result in a higher energy density.

4. How does the energy density of a capacitor compare to other energy storage devices?

In general, capacitors have a lower energy density compared to other energy storage devices, such as batteries. This is because the energy density of a capacitor is dependent on the dielectric constant of the material, while batteries can store energy chemically, resulting in a higher energy density.

5. What are some practical applications of energy density of a capacitor?

The energy density of a capacitor is important in various electronic devices, such as mobile phones, laptops, and cameras, where small and lightweight energy storage is needed. It is also used in electric vehicles, where high energy density capacitors are used for regenerative braking to store energy and improve efficiency.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
912
  • Introductory Physics Homework Help
Replies
26
Views
588
  • Introductory Physics Homework Help
Replies
5
Views
915
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
674
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
20
Views
2K
  • Introductory Physics Homework Help
Replies
9
Views
2K
Back
Top