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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 33

  • question_answer
    Referring to the circuit, R is the resistance of a potentiometer. As the sliding contact is moved from a to b, the reading in the ideal ammeter will                                                                

    A) Increase              

    B)                                  Decrease

    C) Initially decrease and then increase 

    D)  Initially increase and then decrease

    Correct Answer: C

    Solution :

    [c] The total current supplied by source is \[{{I}_{0}}=\frac{{{V}_{0}}}{(R-x)+\frac{rx}{r+x}}\] where x is resistance part of the potentiometer between point a and the sliding contact appearing in parallel with R. Then the current through ammeter \[={{I}_{0}}\times \frac{r}{r+x}\] This current is \[\frac{{{V}_{0}}}{R}\]when \[x=0\]& also when \[x=R.\]                   


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