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

  • question_answer
    A coil of area \[0.4\text{ }{{m}^{2}}\] has 100 turns. A magnetic field of \[0.04\text{ }Wb\text{ }{{\text{m}}^{-2}}\] is acting normal to the coil surface. If this magnetic field is reduced to zero in 0.01 s, then the induced emf in the coil is:

    A) 160 V                           

    B) 250 V  

    C) 270 V                           

    D) 320 V

    Correct Answer: A

    Solution :

    (a) 160 V Here, \[A=0.4\text{ }{{m}^{2}}\text{, }N=100,\text{ }dB=0.04\text{ }Wb\,{{m}^{-2}},\]                         \[dt=0.01\text{ }s\] As   \[\varepsilon =\frac{d\phi }{dt}=NA\frac{dB}{dt}=100\times 0.4\times \frac{0.04}{0.01}=160\,V\]


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