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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 10

  • question_answer
    Every iron-atom in a ferromagnetic domain in iron has a magnetic dipole moment equal to \[9.27\times {{10}^{-24}}A/{{m}^{2}}\]. A ferromagnetic domain in iron has the shape of a cube of side \[1\mu m\]. The maximum dipole moment occurs when all the dipoles are aligned. The molar mass of iron is 56 g and its specific gravity is 8. The approximate magnetization of the domain is

    A) \[8.0\times {{10}^{5}}A/m\]

    B) \[8.0\times {{10}^{8}}A/m\]   

    C) \[8.0\times {{10}^{11}}A/m\]  

    D) \[8.0\times {{10}^{14}}A/m\]

    Correct Answer: A

    Solution :

    [a] Magnetisation \[=\frac{Magnetic\text{ }moment}{volume}\] \[=\frac{9.27\times {{10}^{-24}}\times \frac{Volume\,\times \,density}{Molar\,mass}\times {{N}_{a}}}{Volume}\] \[=\frac{9.27\times {{10}^{-24}}\times 8000\times 6.023\times {{10}^{23}}}{56\times {{10}^{-3}}}=8\times {{10}^{5}}A/m\]


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