- #1
Stendhal
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Homework Statement
A spherical capacitor is formed from two concentric, spherical, conducting shells separated by vacuum. The inner sphere has radius r the capacitance is C.
What is the outer radius R?
Already solved the problem, but I'm more wondering on how to derive the equation that I used.
Homework Equations
Capacitance for a solid inner sphere and outer shell is:
$$\frac {4πε} {\frac {1} {R} - \frac {1} {r}}$$
While for two shells at equal radii, the capacitance is:
$$ \frac {4πε*r*R} {R - r}$$
The Attempt at a Solution
The first equation is simple to figure out, but I'm not really sure how and why making the problem into two shells causes that change.