A) remain unchanged
B) be halved
C) be doubled
D) be quadrupled
Correct Answer: B
Solution :
Key Idea: Conductance is inverse of resistance. Conductance is given by \[\sigma =\frac{1}{R}\] Substituting \[R=\rho \frac{l}{A},\] we get \[\sigma =\frac{A}{\rho l}\] If A = constant, then we have \[\sigma \propto \frac{1}{l}\] \[\Rightarrow \] \[\frac{{{\sigma }_{2}}}{{{\sigma }_{1}}}=\frac{{{l}_{1}}}{{{l}_{2}}}\] Substituting \[{{l}_{2}}=2{{l}_{1}},\] we get \[{{\sigma }_{2}}=\frac{{{\sigma }_{1}}}{2}\] Therefore, conductance will be halved.
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