Question

Intro: A coaxial cable consists of alternating coaxial cylinders ofconducting and insulating material. Coaxial cabling is the primarytype of cabling used by the cabletelevision industry and is alsowidely used for computer networks such as Ethernet, on account ofits superior ability to transmit large volumes of electrical signalwithminimum distortion. Like all other kinds of cables, however,coaxial cables also have some self-inductance that has undesirableeffects, such as producing somedistortion and heating.

Consider a long coaxial cable made of two coaxial cylindricalconductors that carry equal currents I in opposite directions (seefigure). The inner cylinder is a smallsolid conductor of radius a.The outer cylinder is a thin walled conductor of outer radius b,electrically insulated from the inner conductor. Calculatetheself-inductance per unit length frac{L}{l} of this coaxial cable.(Part A 1 figure) ( L is the inductance of part of the cable and lis the length of that part.) Dueto what is known as the "skineffect", the current I flows down the (outer) surface of the innerconducting cylinder and back along the outer surface of theouterconducting cylinder. However, you may ignore the thickness of theouter cylinder.
(Express your answer in terms of someor all the variables ,, , and $mu_0$ , the permeability offree space.)

here's the link with the diagram:
http://session.masteringphysics.com/myct/problemPrint?backViewLink=1&assignmentProblemID=3495184

Answer 1

L = (μ₀/2π)*ln(b/a)

Answer 2

well the question is actually asking for what L/l equals to...anyideas?