A) remain as R
B) become 1.21 R
C) become 1.10 R
D) become 1.20 R
Correct Answer: B
Solution :
Volume remains constant. \[\therefore \] \[{{A}_{1}}{{l}_{1}}={{A}_{2}}{{l}_{2}}\] \[{{A}_{1}}l={{A}_{2}}(1.1l)\] \[{{A}_{1}}={{A}_{2}}(1.1)\] \[{{R}_{1}}=\frac{\rho {{l}_{1}}}{{{A}_{1}}}\] Similarly, \[{{R}_{2}}=\frac{\rho {{l}_{2}}}{{{A}_{2}}}\] \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{\rho \frac{{{l}_{1}}}{{{A}_{1}}}}{\rho \frac{{{l}_{2}}}{{{A}_{2}}}}\] \[=\frac{{{l}_{1}}}{{{A}_{1}}}\times \frac{{{A}_{2}}}{{{l}_{2}}}\] \[=\frac{l}{(1.1){{A}_{2}}}\times \frac{{{A}_{2}}}{(1.1)l}\] \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{1}{1.21}\] \[\Rightarrow \] \[{{R}_{2}}=1.21{{R}_{1}}\]
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