A) the resistance and the specific resistance, will both remain unchanged
B) the resistance will be doubled and the specific resistance will be halved
C) the resistance will be halved and the specific resistance will be remain unchanged
D) the resistance will be halved and the specific resistance will be doubled
Correct Answer: C
Solution :
[c] \[R=\frac{\rho {{\ell }_{I}}}{{{A}_{1}}},\]now \[{{\ell }_{2}}=2{{\ell }_{1}}\] \[{{A}_{2}}=\pi {{\left( {{r}_{2}} \right)}^{2}}=\pi {{\left( 2{{r}_{1}} \right)}^{2}}=4\pi r_{1}^{2}=4{{A}_{1}}\] \[\therefore {{R}_{2}}=\frac{\rho \left( 2{{\ell }_{1}} \right)}{4{{A}_{1}}}=\frac{\rho \,\ell }{2A}=\frac{R}{2}\] \[\therefore \]Resistance is halved, but specific resistance remains the same.You need to login to perform this action.
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