Question

A copper wire has area of cross section 4 into 10 raise to power 9 metre square and resistivity of 1.6 into 10 raise to power minus 8 ohm metre what will be the length of the wire to make its resistance 20 Ohm​

Answer 1

Answer:

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Explanation:

We Know That,

$R=\frac{pl}{A} \\20=\frac{1.6\:X\:10^{-8} X L}{4\:10^{9} } \\20=\frac{1.6\:X\:10^{-1} XL}{4}\\ \frac{4000}{1.6} X\:L\\L=2500m=2km500m$

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