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JEE Main & Advanced JEE Main Paper (Held On 9 April 2017)

  • question_answer
    In a meter bridge experiment resistances are connected as shown in the figure. Initially resistance \[P=4\,\Omega \] and the neutral point N is at 60 cm from A. Now an unknown resistance R is connected in series to P and the new position of the neutral point is at 80 cm from A. The value of unknown resistance R is - [JEE Online 09-04-2017]

    A)  \[\frac{33}{5}\Omega \]                              

    B)  \[5\,\Omega \]

    C)  \[\frac{20}{3}\Omega \]                              

    D)  \[7\,\,\Omega \]

    Correct Answer: C

    Solution :

                    Initially  \[\frac{4}{60}\,=\frac{Q}{40}\,\]               \[Q=\frac{16}{6}=\frac{8}{3}\Omega \]                 Finally                 \[\frac{4+R}{80}=\frac{Q}{20}=\frac{8}{60}\] \[4+R=\frac{64}{6}\] \[R=\frac{64}{6}-4\,=\frac{64-24}{6}=\frac{40}{6}\] \[=\frac{20}{3}\Omega \]


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