Dielectric constant is throwing me off

Click For Summary
SUMMARY

The discussion centers on calculating the radius of the outer sphere of a spherical capacitor with an inner radius of 0.39 m and a capacitance of 108 pF. The formula used is C = K * C * rb - K * C * ra = ra * rb, where K is the constant for vacuum, set to 1. The confusion arises from the interpretation of K, which is clarified as 1/(4∏ε0), not the relative dielectric constant. This distinction is crucial for obtaining the correct answer.

PREREQUISITES
  • Understanding of spherical capacitors and their properties
  • Familiarity with capacitance calculations
  • Knowledge of the vacuum permittivity constant (ε0)
  • Basic algebra for solving equations
NEXT STEPS
  • Review the derivation of capacitance formulas for spherical capacitors
  • Study the concept of vacuum permittivity (ε0) and its role in electrostatics
  • Learn about the implications of dielectric constants in capacitor design
  • Explore practical applications of capacitors in electronic circuits
USEFUL FOR

Physics students, electrical engineers, and anyone involved in capacitor design or electrostatics will benefit from this discussion.

Ahmed.Sandman
Messages
2
Reaction score
0
A spherical capacitor is formed from two concentric, spherical, conducting shells separated by vacuum. The inner sphere has radius 0.39 m and the capacitance is 108 pF. What is the radius of the outer sphere? Give your answer in meters to the third decimal place.

C-->Capacitance
K*C*rb-K*C*ra=ra*rb

it says its a vacuum so I'm using K=1

but I'm not getting a correct answer?!??!
 
Physics news on Phys.org

Similar threads

Why can we model spherical capacitor with two dielectrics as two capacitors in series?
  • · Replies 4 ·
Replies
4
Views
2K
Capacitors: find the dielectric constant
  • · Replies 2 ·
Replies
2
Views
2K
Find the charge on the plates of a parallel-plate capacitor w/ dielectric
  • · Replies 3 ·
Replies
3
Views
2K
Electric Potential at Center of Sphere
  • · Replies 8 ·
Replies
8
Views
10K
Potential in a sphere in a dielectric
  • · Replies 7 ·
Replies
7
Views
7K
Changes in capacitor after dielectric inserted
  • · Replies 17 ·
Replies
17
Views
3K
Electric field of two conducting concentric spheres
  • · Replies 18 ·
Replies
18
Views
5K
Solving Capacitance Problem: Identical Answers Explained
  • · Replies 6 ·
Replies
6
Views
2K
Derivation of capacitance for two shells
  • · Replies 4 ·
Replies
4
Views
2K
Which Equations Apply When a Dielectric is Inserted into a Live Capacitor?
  • · Replies 7 ·
Replies
7
Views
2K