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NEET Sample Paper NEET Sample Test Paper-24

  • question_answer
    The resistances in the two arms of the meter bridge are\[5\Omega \]and \[R\Omega ,\]respectively. When the resistance R is shunted with an equal resistance, the new balance point is at \[1.6{{l}_{1}}.\] The resistance R is

    A) \[10\,\Omega \]                          

    B) \[15\,\Omega \]

    C) \[20\,\Omega \]                          

    D) \[25\,\Omega \]

    Correct Answer: B

    Solution :

     Initially, \[\frac{5}{{{l}_{1}}}=\frac{R}{100-{{l}_{1}}}\]                                  (i) Finally, \[\frac{5}{1.6{{l}_{2}}}=\frac{R}{2(100-1.6{{l}_{1}})}\]                       (ii) \[\Rightarrow \]\[\frac{R}{1.6(100-{{l}_{1}})}=\frac{R}{2(100-1.6{{l}_{2}})}\] \[\Rightarrow \]\[160-1.6{{l}_{1}}=200-3.2\,{{l}_{1}}\] \[\Rightarrow \]\[=1.6{{l}_{1}}=40\] \[\Rightarrow \]\[{{l}_{1}}=25\] From Equation (i), \[\frac{5}{25}=\frac{R}{75}\Rightarrow R=15\,\Omega \]


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