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12th Class Physics Magnetism Question Bank MCQ - Magnetism and Matter

  • question_answer
    A permanent magnet in the shape of a thin cylinder of length 10 cm has magnetisation\[(M)={{10}^{6}}A{{m}^{-1}}\]. It’s magnetisation current \[{{l}_{M}}\] is:

    A) \[{{10}^{5}}A\]                      

    B)             \[{{10}^{6}}A\]

    C)             \[{{10}^{7}}A\]                      

    D)             \[{{10}^{8}}A\]

    Correct Answer: A

    Solution :

    (a) \[{{10}^{5}}A\]                                              As         \[Bl={{\mu }_{0}}Ml={{\mu }_{0}}(l+{{l}_{M}})\]       Here,     \[l=0\] Then    \[{{\mu }_{0}}Ml={{\mu }_{0}}({{l}_{M}})\] \[\Rightarrow {{l}_{M}}=Ml={{10}^{6}}\times 0.1={{10}^{5}}A\]


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