JEE Main & Advanced Physics Magnetism Question Bank Assertion and Reason

  • question_answer
    Assertion             :       For a perfectly diamagnetic substance permeability is always one. Reason                 :       The ability of a material of permit the passage of magnetic lines of force through it is called magnetic permeability.

    A)             If both assertion and reason are true and the reason is the correct explanation of the assertion.

    B)             If both assertion and reason are true but reason is not the correct explanation of the assertion.

    C)             If assertion is true but reason is false.

    D)             If the assertion and reason both are false.

    E)             If assertion is false but reason is true.

    Correct Answer: E

    Solution :

                       For a perfectly diamagnetic substance, \[B={{\mu }_{0}}(H+I)=0\]          \[\therefore \,I=-H.\] Therefore, \[{{\chi }_{m}}=\frac{I}{H}=-1\] Therefore relative permeability \[{{\mu }_{r}}=1+{{\chi }_{m}}=1-1=0.\] \[\therefore \,\,\mu ={{\mu }_{0}}{{\mu }_{r}}=\]zero. i.e. for a perfectly diamagnetic material permeability is zero.


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