Yahoo Answers: Answers and Comments for What is the capacitance in pF? [Engineering]
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From Anonymous
enUS
Sun, 23 Sep 2012 15:53:55 +0000
3
Yahoo Answers: Answers and Comments for What is the capacitance in pF? [Engineering]
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https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
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From Iby K: sure it is working, you just need to keep trac...
https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
Sun, 23 Sep 2012 23:00:59 +0000
sure it is working, you just need to keep track of units  in metric system, unit of length is meter, not cm, mm, km etc.
so
A=0.03x0.03=0.0009 m^2
D=0.0007 m
ε0 ≈ 8.854187817620... × 10−12 F/m
or
ε0 ≈ 0.000000000008854187817620 F/m
you get
C=1.1384x10^11F
or about 0.114pF

From Roger: The capacitor
c = εo(A)/d where εo = 8.854 x ...
https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
Sun, 23 Sep 2012 23:25:58 +0000
The capacitor
c = εo(A)/d where εo = 8.854 x 10^12 Farad/meter
the plate area is (3cm)(3 cm) = 9 cm^2 which in square meters is
A = 9 x 10^4 m^2
The distance between the plates is 0.7 mm which in meters is
d = 7 x 10^4 m
c = (8.854 x 10^12F/m)(9 x 10^4 m^2)/ (7 x 10^4 m) = 1.14 x 10^11F ≈ 11 pF where pF is pico Farad which is 1 x 10^ 12 Farads

From Rick: You have to use the correct units. Distance i...
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https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
Sun, 23 Sep 2012 23:12:03 +0000
You have to use the correct units. Distance in meters, area in meter squared and eo in F/meter. It will work then. BTW, the correct equation is C=eo er A/D. er is 1 for air.

From Len: Capacitance C = (0.0885 KA) divided by d, or C...
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https://answers.yahoo.com/question/index?qid=20120923155354AA785mK
Sun, 23 Sep 2012 23:07:53 +0000
Capacitance C = (0.0885 KA) divided by d, or C = (0.224 KA) divided by d.
In the first formula "A" is the area of the overlap and is in square centimetres and "d" the distance apart is in centimetres.
In the second formula "A" is in square inches and "d" is in inches. "K" is the dielectric constant.
The K of a vacumm is 1. Air is slightly more.