26. Capacitors & Dielectrics

"A coaxial cable, Fig. 24–35, consists of an inner cylindrical conducting wire of radius R₆ surrounded by a dielectric insulator. Surrounding the dielectric insulator is an outer conductor of radius Rₐ, which is usually “grounded.”

(a) Determine an expression for the capacitance per unit length of a cable whose insulator has dielectric constant K.

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A coaxial cable, Fig. 24–35, consists of an inner cylindrical conducting wire of radius R₆ surrounded by a dielectric insulator. Surrounding the dielectric insulator is an outer conductor of radius Rₐ, which is usually “grounded.”

(b) For a given cable, R₆ = 2.5 mm and Rₐ = 9.0 mm. The dielectric constant of the dielectric insulator is K = 3.2. Suppose that there is a potential of 1.0 kV between the inner conducting wire and the outer conducting sheath. Find the charge, and capacitance, per meter of the cable.

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