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

  • question_answer
    A solenoid 30 cm long is made by winding 2000 loops of wire on an iron rod whose cross-section is \[1.5\text{ }c{{m}^{2}}\]. If the relative permeability of iron is 6000. What is the self-inductance of the solenoid?

    A) 25 H                            

    B) 5 H     

    C) 15 H                            

    D) 35 H

    Correct Answer: C

    Solution :

    (c) 15 H Here, \[{{\mu }_{r}}=6000,\,\,l=30\,cm=0.3\,m,\,N=2000,\] \[A=1.5\,c{{m}^{2}}=1.5\times {{10}^{-4}}{{m}^{2}}\] \[L=\frac{{{\mu }_{r}}{{\mu }_{0}}{{N}^{2}}A}{l}\] \[=\frac{6000\times 4\pi \times {{10}^{-7}}\times {{(2000)}^{2}}\times 1.5\times {{10}^{-4}}}{0.3}\] \[=15\,H\]


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