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Question
The plates of a parallel-plate capacitor are made of circular discs of radii 5⋅0 cm each. If the separation between the plates is 1⋅0 mm, what is the capacitance?
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Solution
The capacitance of a parallel-plate capacitor is given by `C = (∈_0A)/d`
Here ,
A = Area of the plate
d = Distance between the parallel plates
Given :
`A = pir^2 = pi xx (5 xx 10^-2)^2`
`d = 1.0 xx 10^-3 "m"`
`∈_0 = 8.85 xx 10^-12 F/m`
`therefore C = (∈_0A)/d`
= `(8.85 xx 10^-12 xx 3.14 xx 25 xx 10^-4)/10^-3`
= `6.95 xx 10^-5 uF`
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