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Physics/farads in a sphere

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Question
QUESTION: hello, THIS IS NOT A HOMEWORK QUESTION I AM 38YO!
please tell me how i can work out how many farads would be stored in a sphere of 75cm?
also how big a sphere would be to store a 0.1 microfarad.
THANK YOU,
Gene

ANSWER: http://en.wikipedia.org/wiki/Capacitance#Self-capacitance
That's pretty much all you need, that formula, for both of those.

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QUESTION: please tell me, in the formula given in the article how do i do that sum on the calculator in windows7. i do not see the Eo button. please could you write it out so i can follow the template. also there is the google calculator that might be suitable. but i do not know how to punch it in. also how do i put in the air & surface quantities (or are they insignificant).
thank you,
Gene

ANSWER: It's not a button on a calculator, it's a physical constant for empty space (nearly identical to air).  From earlier in the article, "ε0 is the electric constant (ε0 ≈ 8.85410−12 F m1)."  R is obviously the radius. There's no sum, you just multiply the terms.

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QUESTION: thank you,
so i do:
4 x π x ε0 x R =
R is in cm?
but how do i put the ε0 into the equation?
thank you,
gene

Answer
I just gave you the number, 8.85410−12 F/m.  The radius R is obviously in meters so that it cancels with the m in F/m to leave you with Farads (F).  Why did you put n in the equation instead of pi?  Nevermind, just multiply those four numbers.  Windows has a calculator built in.

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Dr. Stephen O. Nelson

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I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

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I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

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Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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