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12th Class Physics Electro Magnetic Induction Question Bank MCQ - Electromagnetic Induction

  • question_answer
    A circular disc of radius 0.2 m is placed in a uniform magnetic field of induction \[\frac{1}{\pi }\left( \frac{Wb}{{{m}^{2}}} \right)\] in such a way that its axis makes an angle of \[60{}^\circ \] with B. The magnetic flux linked with the disc is:

    A) 0.02 Wb                       

    B) 0.06 Wb

    C) 0.08 Wb                       

    D) 0.01 Wb

    Correct Answer: A

    Solution :

    (a) 0.02 Wb Here, \[\theta =60{}^\circ ,\text{ }B=\frac{1}{\pi }Wb{{m}^{-2}}\text{, }A=\pi {{\left( 0.2\text{ } \right)}^{2}}\] \[\therefore \phi =BA\,\cos \theta \Rightarrow \,\phi =\frac{1}{\pi }\times \pi {{(0.2)}^{2}}\times \cos \,60{}^\circ \]                         \[={{(0.2)}^{2}}\times \frac{1}{2}=0.02\,Wb\]


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