Electrostatics : An air-filled coaxial cable

Problem statement

Consider an air-filled cable, where the inner conductor is supported periodically so that it is essentially surrounded be air.

Objective : to find the capacitance C of the cable.
Principles : Gauss' law.

Method of analysis :	1) define the potential difference V between conductors,
			2) define the charge per unit length [rho] on the inner conductor.

Sketch :

Maths :

Matlab(R) solution
Solution variables
Input variables



Charge per unit length, q (Coulombs/metre)	
Radius of outer conductor, b (metres)		
Radius of inner conductor, a (metres)		
Radius from centre, r (metres)			



Output variables


Electric field strength, E
Potential difference between the conductors, V
Capacitance per unit length, C