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JEE Main & Advanced JEE Main Online Paper (Held on 9 April 2013)

  • question_answer
                                    In a metre bridge experiment null point is obtained at 40 cm from end of the wire when resistance X is balanced against another resistance Y. if X < Y, then the new position of the null point from the same end, if one decides to balance a resistance of  3X  against Y, will be close to :                     JEE Main Online Paper (Held On 09 April 2013)

    A)                 80 cm                                   

    B)                 75 cm                 

    C)                                        67 cm                   

    D)                        50 cm                

    Correct Answer: C

    Solution :

                    As \[\frac{x}{y}=\frac{40}{100-40}=\frac{40}{60}\]                 \[\frac{3x}{y}=3\left( \frac{40}{60} \right)=\frac{120}{60}=\frac{2}{1}\]                 Now, the total length = 100 \[\therefore \] Required length \[=\frac{100}{3}\times 2=67\,m\].                


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