P26_037.PDF

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Chapter 26 - 26.37

37. The capacitance of a cylindrical capacitor is given by

C = κC 0 = 2 πκε 0 L

ln( b/a ) ,

where C 0 is the capacitance without the dielectric, κ is the dielectric constant, L is the length, a is the

inner radius, and b is the outer radius. The capacitance per unit length of the cable is

L =

ln( b/a ) = 2 π (2 . 6)(8 . 85

10 − 12 F / m)

ln[(0 . 60 mm) / (0 . 10 mm)]

=8 . 1

10 − 11 F / m=81pF / m .

2 πκε 0