Capacitance of two parallel plate capacitors

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Homework Help Overview

The discussion revolves around calculating the capacitance of two square metal plates separated by a distance in a vacuum. The subject area is capacitance in the context of electrostatics, specifically focusing on parallel plate capacitors.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of area for the plates and the separation distance. There are questions about how to determine the area based on the dimensions provided and the relationship between the area and distance in the capacitance formula.

Discussion Status

Participants are actively clarifying the definitions of the variables involved, particularly the area of the plates and the separation distance. Some guidance has been provided regarding the interpretation of the dimensions, and there is an acknowledgment of a potential misunderstanding regarding the problem setup.

Contextual Notes

There is a note about the title of the thread potentially being misleading, as it suggests there are two capacitors when it is actually one capacitor formed by two plates. Participants are also considering whether a reevaluation of the problem is necessary based on the clarifications provided.

Violagirl
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Homework Statement



Two square metal plates with sides of length 0.1 m are separated in vacuum by 10-3 m. Find their capacitance.

Homework Equations



C = Q/V

For a parallel plate capacitor:

C = E0A/L


The Attempt at a Solution



If A is supposed to be the length of the metal plates with 0.1 m, since A has units of m2, I took A = (.1m)2 = .01 m2 and L = 10-3 m.

From there and plugging everything in, I get:

C = (8.85 x 10-12 C2/N m2 * .01m2/10-3 m

C = 8.85 x 10-11 Farads

If someone could confirm whether this is correct or not, I would appreciate it.
 
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Violagirl said:
If A is supposed to be the length of the metal plates with 0.1 m, since A has units of m2, I took A = (.1m)2 = .01 m2 and L = 10-3 m.
A is the area of each plate. (The area of one face of a plate.)
 
Right about A. What I meant was, of the two numerical values that I'm provided, which would be my A? Or how do I determine my A? I know then that my separation distance corresponds to L. So do I need to determine A by my length values in this situation?
 
A is the area of the square plate. It's 0.1m per side, so A = (0.1m)² as you showed.
 
Violagirl said:

Homework Statement



Two square metal plates with sides of length 0.1 m
This is the dimension of plate.
are separated in vacuum by 10-3 m. Find their capacitance.

This is the distance between the plate
Do not get confused by them. Dimensions of the plate has nothing to do with distance between the plates.

(Also the title is wrong there's only one parallel plate capacitor here, two plates make a capacitor.)
 
Enigman said:
This is the dimension of plate.


This is the distance between the plate
Do not get confused by them. Dimensions of the plate has nothing to do with distance between the plates.

(Also the title is wrong there's only one parallel plate capacitor here, two plates make a capacitor.)

Oh shoot! I did not realize that. Do I need to redo this problem then and look at other equations to determine capacitance then?
 
Er...no everything is correct; just show how you found area by the dimensions given.
 
Oh got it! Will do, thanks so much for looking at this!
 

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