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CMC Medical CMC-Medical Ludhiana Solved Paper-2012

  • question_answer
    A cylindrical metal wire of length \[l\] and cross-sectional area S, has resistance R, conductance G, conductivity \[\sigma \] and resistivity\[\rho \]. Which one of the following expression for\[\sigma \]is valid?

    A)  \[\frac{GS}{l}\]                                

    B)  \[\frac{Rl}{S}\]

    C)  \[\frac{GR}{\rho }\]                                      

    D)  \[\frac{\rho R}{G}\]

    Correct Answer: C

    Solution :

                    We know that, conductivity        \[\sigma =\frac{1}{\rho }\]                           ?(i) and conductance,\[G=\frac{1}{R}\]              ...(ii) \[\Rightarrow \]               \[GR=1\] From Eqs. (i) and (ii), we get \[\sigma =\frac{GR}{\rho }\]


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