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JEE Main & Advanced Physics Magnetism Question Bank Self Evaluation Test - Magnetism and Matter

  • question_answer
    A bar magnet has coercivity \[4\times {{10}^{5}}\,A{{m}^{-1}}\]. It is desired to demagnetise it by inserting it inside a solenoid 12 cm long and having 60 turns. The current that should be sent through the solenoid is

    A) 2 A      

    B) 4 A  

    C) 6 A      

    D) 8 A

    Correct Answer: D

    Solution :

    [d] \[n=\frac{N}{l}=\frac{60}{0.12}=500\,\,\,turn\,\,\,metr{{e}^{-1}}\] \[\Rightarrow \,\,\,i=\frac{H}{n}=\frac{4\times {{10}^{3}}}{500}=8A\]


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