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NTSE Sample Paper NTSE SAT Practice Test-20

  • question_answer
    A piece of wire is divided in four equal parts They are put together to form a bundle. The resistance of the bundle as compared to that of original wire will be                

    A) \[\frac{1}{4}\]                          

    B) \[\frac{1}{6}\]

    C) \[\frac{1}{8}\]                          

    D) \[\frac{1}{16}\]

    Correct Answer: D

    Solution :

    [d] \[R=\rho \frac{a}{\Alpha }\] and \[{{R}^{'}}=\rho \frac{{{l}^{'}}}{{{\Alpha }^{'}}}\] Here \[{{1}^{'}}=\frac{1}{4}\]and \[{{A}^{'}}=4A\] \[\therefore \,\,\,{{R}^{'}}=\rho \frac{l/4}{4A}=\frac{1}{16}\,\,\rho \frac{1}{A}=R/16\]


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