- #1
amcavoy
- 665
- 0
I said that [itex]A\ell=A_{\textrm{new}}\ell\left(1+\frac{x}{100}\right)\implies A_{\textrm{new}}=\frac{A}{1+\frac{x}{100}}[/itex]. Also, we know that [itex]R\propto\frac{\ell}{A}.[/itex]. Therefore,A cylindrical wire of length [itex]\ell[/itex] and cross-sectional area [itex]\textrm{A}[/itex] has a fixed volume [itex]\textrm{V}[/itex]. If [itex]\ell[/itex] is increased by [itex] +x [/itex] percent and the volume and resistivity stay the same, by what percentage (in terms of [itex]x[/itex]) will the resistance change?
[tex]R_{\textrm{old}}\propto\frac{\ell}{A}[/tex]
[tex]R_{\textrm{new}}\propto\frac{\ell\left(1+\frac{x}{100}\right)^{2}}{A}[/tex]
Somehow I'm not getting as nice of an answer as I expected.
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