contestada

A silver wire is 0.04 mm it is used to make a resistance of 1ohm if the resistivity of silver is 1.6*10^-8 then calculate the length of the wire needed

Respuesta :

Answer:

[tex]l=7.853\ cm\approx0.079\ m[/tex]

Explanation:

Given:

  • thickness of silver wire, [tex]d=0.04\ mm=4\times 10^{-5}\ m[/tex]
  • resistivity of silver, [tex]\rho=1.6\times 10^{-8}\ \Omega.m[/tex]
  • resistance, [tex]R=1\ \Omega[/tex]

As we know, resistance:

[tex]R=\rho \frac{l}{a}[/tex]

[tex]1=1.6\times 10^{-8}\times \frac{l}{\pi.\frac{d^2}{4} }[/tex]

[tex]\frac{1}{1.6} \times 10^8\times \pi\times \frac{(4\times 10^{-5})^2}{4} =l[/tex]

[tex]l=7.853\ cm\approx0.079\ m[/tex]

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