Question

A silver wire 2m long is to have a resistance of 0.5ohm.What should its diameter be?

Answer 1

simple

\[\rho(resistivity)=1.59*10^{-8}\Omega m\]
this value is for silver just.

use the formula,
\[R=\rho L/A\]
\[A=\rho L/R\]
\[\pi(d/2)^{2}=\rho L/A\]
\[(d/2)^{2}=\rho L/\pi A\]
\[(d/2)=\sqrt{\rho L/\pi A}\]
\[d=2\sqrt{\rho L/\pi A}\]

now you can calculate diameter by using above formula.

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