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NEET AIPMT SOLVED PAPER SCREENING 2004

  • question_answer
    Resistances n, each, of r ohm, when connected in parallel give an equivalent resistance of R ohm. If these resistances were connected in series, the combination would have a resistance in ohms, equal to:

    A) \[{{n}^{2}}R\].                                                                      

    B) \[R/{{n}^{2}}\]                                                                      

    C) R/n                

    D) nR

    Correct Answer: A

    Solution :

    Equivalent resistance of n resistances each of r     ohm in parallel is given by \[\frac{1}{R}=\frac{1}{r}+\frac{1}{r}+.................+n\]times\[=\frac{n}{r}\] so,\[r=nR\] When these resistances are connected in series, effective resistance is \[R'=r+r+........+n\]times\[=nr\] \[\therefore \]\[R'=n\,(nR)={{n}^{2}}R\]


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