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

  • question_answer
    At a certain location in Africa, compass points \[12{}^\circ \] west of geographic north. The north tip of magnetic needle of a dip circle placed in the plane of magnetic meridian points \[60{}^\circ \] above the horizontal. The horizontal component of Earth's magnetic field is measured to be 0.16 G. The magnitude of Earth's magnetic field at the location is:

    A) 0.32 G                         

    B)             0.42 G     

    C)             4.2 G                           

    D)             3.2 G

    Correct Answer: A

    Solution :

    (a) 0.32 G Here, \[{{H}_{E}}=0.16\,G,=0.16\times {{10}^{-4}}T,\] dip angle \[\delta =60{}^\circ \] Then, magnitude of Earth's magnetic field,             \[{{B}_{E}}=\frac{{{H}_{E}}}{\cos \delta }=\frac{0.16\times {{10}^{-4}}}{\cos \,60{}^\circ }T\] \[\Rightarrow \,\,\,\,\,\,{{B}_{E}}=\frac{0.16\times {{10}^{-4}}}{1/2}=0.32\times {{10}^{-4}}T=0.32\,G\]


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