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

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SUMMARY

The discussion focuses on the relationship between plate radius and capacitance in a parallel plate capacitor. The capacitance formula C = ε*A/d is central to the analysis, where ε represents permittivity, A is the area of the plates, and d is the separation distance. To achieve a capacitance of 2.8 microfarads with a plate separation of 1.6mm, the radius must be calculated using the area formula A = πR². Additionally, if the separation distance decreases, the radius of the plates must be increased to maintain the same capacitance. For a plate separation of 3mm, the radius can also be determined using the same capacitance formula.

PREREQUISITES
  • Understanding of capacitance and the formula C = ε*A/d
  • Familiarity with the concept of permittivity (ε) and its significance
  • Knowledge of geometric area calculations, specifically for circles (A = πR²)
  • Basic grasp of electrical concepts related to capacitors
NEXT STEPS
  • Calculate the radius of a parallel plate capacitor for various capacitance values using C = ε*A/d
  • Explore the effects of varying plate separation on capacitance in practical applications
  • Investigate the role of different materials on permittivity (ε) in capacitors
  • Learn about the implications of capacitor design in electronic circuit applications
USEFUL FOR

This discussion is beneficial for electrical engineers, physics students, and anyone involved in designing or analyzing capacitors and their performance in electronic circuits.

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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