Coaxial cable has radius a of copper core and radius b of copper shield. Between there is an insulator with specific resistivity ζ. What is the resistance of this cable with length L between the core and the shield?First, I tried to solve this like this: d R = ζ l S In our case the length is dr, and therefore I suppose that the area of this ring is 2πrdr: d R = ζ d r 2 π r d r The solution sheet says: d R = ζ d r 2 π r L I know that something is wrong with my equation, because dr goes away and then I cannot integrate from a to b. But why is in the solution L instead of dr? As I understand problem instruction L= b-a. And therefore L=dr which doesn't make sense to me.

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Coaxial cable has radius a of copper core and radius b of copper shield. Between there is an insulator with specific resistivity   ζ. What is the resistance of this cable with length L between the core and the shield?First, I tried to solve this like this:   d  R  =  ζ      l    S  In our case the length is dr, and therefore I suppose that the area of this ring is 2πrdr:   d  R  =  ζ            d      r              2              π            r      d      r       The solution sheet says:   d  R  =  ζ            d      r              2              π            r      L      I know that something is wrong with my equation, because dr goes away and then I cannot integrate from a to b. But why is in the solution L instead of dr? As I understand problem instruction L= b-a. And therefore L=dr which doesn&#039;t make sense to me.

Layne Bailey · Accepted Answer

The area of your element is   2  π  r  L and the thickness of your element is   d  r

Coaxial cable has radius a of copper core and radius b of copper shield. Between there is an insulat

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