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NEET Sample Paper NEET Sample Test Paper-68

  • question_answer
    The current through a 4.6 H inductor is shown in the following graph. The induced emf during the time interval \[\operatorname{t} \,=\, 5\] milli-sec to 6 milli-sec will be  

    A) \[{{10}^{3}}\,V\]                    

    B) \[-23\times {{10}^{3}}\,V\]

    C) \[23\times {{10}^{3}}\,V\]                   

    D) Zero

    Correct Answer: C

    Solution :

    Rate of decay of current between \[t=5\,ms\] and 6 ms \[=\,\,\frac{di}{dt}\,\,=\,\,-(Slope\,\,of\,\,the\,\,line\,\,BC)\] \[=\,\,-\left( \frac{5}{1\times {{10}^{-3}}} \right)\,\,=\,\,-5\times {{10}^{3}}\,A/s\] Hence induced emf \[e=-L\frac{di}{dt}\,\,=\,\,-4.6\times (-5\times {{10}^{3}})=23\times {{10}^{3}}\,V\,\]


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