The resistance of a $5\, cm$ long wire is $10\, \Omega$. It is uniformly stretched so that its length becomes $20\, cm$. The resistance of the wire is ............. $\Omega$
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(a) $\frac{{{R_1}}}{{{R_2}}} = {\left( {\frac{{{l_1}}}{{{l_2}}}} \right)^2}$$ \Rightarrow \,\,\,\frac{{10}}{{{R_2}}} = {\left( {\frac{5}{{20}}} \right)^2} = \frac{1}{{16}} = {R_2} = 160\,\Omega $.
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Statement $II$ : The resistivity of the material is independent of temperature.
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