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Calculation of capacitance of concentric cylinders using the formula [ C = 2 x Pi x  εo x εr / Log( D/d ) ]

D is the Inside Diameter of the Outer tube in mm,
d is the Outside Diameter of the Inner tube in mm.
εr is the permittivity or dielectric constant (k) between the tubes.(Air = 1)

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 D ( Inside Diameter of outer tube in mm )
 d ( Outside Diameter of inner tube in mm )
 Length of tube overlap in mm
 k (dielectric constant of insulation)
Some Common Dielectrics

Capacitance of chosen length in pF
Capacitance in pF per metre
Capacitance in pF per foot
 maximum thickness of dielectric in mm
 Impedance in ohms
 Velocity factor
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Page Last updated 21st July 2013