Question

The electrical resistance of a wire varies directly with the length and inversely with the square of the diameter of the wire. If a wire 432 feet long and 4 millimeters in diameter has a residence of 1.24 ohms, find the length of a wire of the same material whose resistance is 1.44 ohms and whose diameter is 3 millimeters

Answer 1

Hello,

$\boxed{R=k* \dfrac{l}{D^2} }\\\\ 1)k=R* \dfrac{D^2}{l} =1.24* \dfrac{4^2}{432} \\ 2)l=R* \dfrac{D^2}{l} =1.44* \dfrac{3^2}{1.24*\frac{16}{432}} =282.1935...(feet)$

Answer 2

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