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jacobier
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Is it any model on resisivity of two tightly-attached coaxial cylinder? For example, a copper core wire is coated with layer of aluminum. How to calculate the final resistivity along axis?
Hassan2 said:add together the resistance of the core and the shield.
haruspex said:I don't think you mean add the resistances together. These are in parallel here, so it's the conductances that add.
jacobier said:Thank you very much. Actually I mean "resistance". I have been looking for solution for this for a long time. Probably the problem is not as complicated as I thought, no one have interest to talked about that.
I get the feeling you have the wrong model for the set-up. There's a copper core and an Al coating. The axial current will consist of some current in each, in parallel. At each end there may be some radial flow, but I'm assuming we can ignore that.Hassan2 said:Actually what I had in mind is that the two , with a load connected to the end form a series circuit, that's why i added the " resistances" together. (OP asked about resistance along the axis.)
Hassan2 said:marcusl and haruspex,
In the attached figure, aren't the series resistances of the core and the shield added together to give the cable resistance? Sorry I understand that this is very simple question but I would like to know what I am not getting.
Thanks.
The formula for calculating the resistivity of coaxial cylinders is ρ = (ln(b/a))/(2πL), where ρ is the resistivity, b is the outer radius of the cylinder, a is the inner radius of the cylinder, and L is the length of the cylinder.
The units of resistivity for coaxial cylinders are ohm-meters. This is derived from the formula ρ = RA/L, where R is the resistance, A is the cross-sectional area, and L is the length of the cylinder. Therefore, the units of resistivity are ohms (Ω) divided by meters (m).
The inner and outer radii of a coaxial cylinder can be measured using a caliper or a ruler. Place the measuring tool directly on the surface of the cylinder and take the measurement in either millimeters or centimeters. Be sure to measure the inner radius from the inside edge of the cylinder and the outer radius from the outside edge.
Yes, the formula ρ = (ln(b/a))/(2πL) can be used to calculate the resistivity of any coaxial cylinder, regardless of the material. This formula is based on the dimensions of the cylinder and does not depend on the material properties.
The calculated resistivity for coaxial cylinders can be very accurate if the measurements of the inner and outer radii are precise. However, there may be slight variations due to imperfections in the cylinder's shape or material properties. It is always best to take multiple measurements and calculate the average resistivity for more accurate results.