BCECE Medical BCECE Medical Solved Papers-2014

  • question_answer
    The specific resistance of a wire is \[\rho \], its volume is \[3{{m}^{3}}\] and its resistance is \[3\,\,\Omega \], then its length will be

    A)  \[\frac{3}{\sqrt{\rho }}\]                  

    B)  \[\frac{\sqrt{3}}{\rho }\]

    C)  \[\frac{5}{\sqrt{\rho }}\]                   

    D)  \[\frac{\sqrt{5}}{\rho }\]

    Correct Answer: A

    Solution :

    Volume = Area \[\times \] length                 \[3=Al\]                 \[A=\frac{3}{l}\] Resistance \[R=\rho \frac{l}{A}\]                 \[3=\frac{\rho l}{\left( \frac{3}{l} \right)}=\frac{\rho {{l}^{2}}}{3}\]                 \[{{l}^{2}}=\frac{9}{\rho }\] \[\Rightarrow \] \[l=\frac{3}{\sqrt{\rho }}\]


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