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

  • question_answer
              A magnetising field of \[2\times {{10}^{3}}A{{m}^{-1}}\]produces a magnetic flux density of \[8\pi T\] in an iron rod. The relative permeability of the rod will be:

    A) \[{{10}^{2}}\]                        

    B)             1         

    C)             \[{{10}^{4}}\]                        

    D)             \[{{10}^{3}}\]        

    Correct Answer: C

    Solution :

    (c) \[{{10}^{4}}\] Here,   \[H=2\times {{10}^{3}}A{{m}^{-1}}\], \[B=8\pi \,T,\text{ }{{\mu }_{0}}=4\pi \times {{10}^{-7}}\] Since \[{{\mu }_{r}}=\frac{\mu }{{{\mu }_{0}}}=\frac{\mu H}{{{\mu }_{0}}H}=\frac{B}{{{\mu }_{0}}H}\] \[=\frac{8\pi }{4\pi \times {{10}^{-7}}\times 2\times {{10}^{3}}}={{10}^{4}}\]


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