Anonymous asked in Science & MathematicsPhysics · 5 months ago

I have V, and current for different lengths. I can get R with R=V/length. How does cross sectional area relate to the R vs. length graph?


Ok, thank you for your help. I am trying to find the cross sectional area. I think I'm confused about how to find the C.S.A because I wasn't given ρ (rho). The slope of my Resistance vs. Length graph is 8.7. I would have to manipulate --> R = ρℓ / A into A = ρℓ / R . I would have the values of R and ℓ but I would have two unknowns ρ and A.

2 Answers

  • NCS
    Lv 7
    5 months ago
    Favorite Answer

    It is not true that R=V/length.

    You can get resistance R = V / I

    where I ("eye") is the current (not l ("ell"), the length)

    Furthermore, if you plot R vs length, you must hold the cross-sectional area constant in order to get a meaningful graph.

    It might be better to explain what your objective is. I suspect that it is to calculate the resistivity ρ of the wire material.

    R = ρℓ / A

    so, if you plot R (vertical) vs ℓ/A (horizontal) the slope of the line shoud be the resistivity of the conductor.

    If you find this helpful, please award Best Answer!

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  • 5 months ago

    Although I could give you the answer there is nothing in the question that gives any clues.

    If this was an experiment you would be expected to take a number of pieces of wire of the same length but different diameters and discover the result.

    If you take the theory you know that Resistance = resistivity ( a constant) * L/A

    so that the gradient of the graph of R vs L is R/L = resistivity / A

    ie the gradient of your graph is inversely proportional to the cross sectional area A

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