How Does Changing Plate Radius Affect Capacitance in a Parallel Plate Capacitor?

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Homework Help Overview

The discussion revolves around the relationship between the radius of plates in a parallel plate capacitor and its capacitance. The original poster presents a problem involving specific capacitance values and plate separation distances, prompting questions about how changes in these parameters affect capacitance.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the formula for capacitance, questioning how the radius and separation distance relate to maintaining a specific capacitance. There are attempts to clarify the meaning of variables in the capacitance formula and how they apply to the problem.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the concepts involved. Some guidance has been provided regarding the formula for capacitance, but confusion remains about the variables and their implications. Multiple interpretations of the problem are being explored.

Contextual Notes

Participants note the lack of certain information, such as the permittivity value and its relevance to the calculations. There is also uncertainty about the relationship between plate radius and separation distance in the context of capacitance.

papi
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Consider a parallel plate capacitor constructed from two circular metal plates of radius R. The plates are separated by a distance of 1.6mm

a. What radius must the plates have if the capacitence is 2.8 micro F?

b. if the separation between the plates is decreased, should the radius of the plates be increased or decreased to maintain the capacitence? PLEASE EXPLAIN

c. Find the radius of the plates that gives a capacitence of 2.8 micro F for a plate separation of 3 mm

I know C=Q/V but how does that help here?
 
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i still don't get it at all. would d=2R and I don't know the E here.. it isn't given
 
papi said:
i still don't get it at all. would d=2R and I don't know the E here.. it isn't given

Throw me a bone here. It's not E. It's ε - permittivity. It would be εo for air. A is area (the radius might help with that) and d is the distance between the plates.

Try reading the link again if you are confused.
 

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