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BHU PMT BHU PMT (Mains) Solved Paper-2007

  • question_answer
    There is magnetic material of coercivity\[2\times {{10}^{3}}A/m\]. What current should flow through solenoid of length 15 cm having 150 turns 150 to demagnetize the substance completely?

    A)  4 A                                        

    B)  2.5 A

    C)  2 A                                        

    D)  3.5 A

    Correct Answer: C

    Solution :

                     \[Coercivity=ni\] where n is number of turns per metre length of solenoid. \[\therefore \]  \[2\times {{10}^{3}}=\frac{150}{0.15}i\]or             \[i=2A\]


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