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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 8

  • question_answer
    Figure shows a potentiometer arrangement with \[{{R}_{AB}}=10\,\Omega \] rheostat of variable resistance x. For \[x=0,\] null deflection point is found at 20 cm from A. For unknown value of x null deflection point was at 30 cm from A, then the value of x is

    A) \[10\,\Omega \]

    B) \[5\,\Omega \]

    C) \[2\,\Omega \]               

    D) \[1\,\Omega \]

    Correct Answer: B

    Solution :

    [b] \[\left( \frac{E}{\ell } \right)\times 20={{E}_{0}}\] \[\frac{\left[ E-\left( \frac{E}{10+x} \right)x \right]}{\ell }\times 30={{E}_{0}}\] \[1=\frac{3x}{10+x};\,\,\,x=5\Omega \]


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