A) 1.2 times, 1.1 times
B) 1.21 times, same
C) Both same
D) 1.1 times, 1.1 times
Correct Answer: B
Solution :
[b] When wire is stretched by 10% \[{{V}_{1}}={{V}_{2}}\] (remains same) \[\pi r_{{}^\circ }^{2}{{\ell }_{{}^\circ }}=\pi r_{1}^{2}\left[ {{\ell }_{{}^\circ }}+\frac{10}{100}{{\ell }_{{}^\circ }} \right]\] \[r_{{}^\circ }^{2}{{\ell }_{{}^\circ }}=r_{1}^{2}\frac{11}{10}{{\ell }_{{}^\circ }}\] \[{{R}_{{}^\circ }}=\ell \frac{{{\ell }_{{}^\circ }}}{\pi r_{{}^\circ }^{2}}........(1)\] \[{{R}_{1}}=\ell \frac{\left[ \frac{11}{10}{{\ell }_{{}^\circ }} \right]}{\pi r_{1}^{2}\left( \frac{10}{11}r_{{}^\circ }^{2} \right)}=\frac{\ell (121){{\ell }_{{}^\circ }}}{\pi (100)r_{{}^\circ }^{2}}........(2)\] \[{{R}_{1}}=1.21{{R}_{{}^\circ }}\] While resistivity depends upon material nature rather on material dimension.
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