The plates of a spherical capacitor have radii 43.5 mm and 46.7 mm. (a) Calculate the capacitance in picofarads. (b) What must be the plate area in square centimeters of a parallelplate capacitor with the same plate separation and capacitanc
1 Answer

C = (4πε0)(ab/(ab)) = (4*pi*8.85*10^12)*[(43.5*46.7*10 ^6)/[(46.743.5)*10^3] = 7.076*10 ^11 f or
Required capacitance = 70.76 pF
Equivalent parallel cpacitance should have area A given by
(8.85*10^12)*A/(3.2*10^3) = 70.76*10^12 or
A = [70.76*3.2*10^3]/8.85 = 0.0256 m^2 = 256 cm^2