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

  • question_answer
    The number of turns and length of the solenoid are both doubled, keeping area of cross-section of the solenoid same. Then self-inductance of the coil will be:

    A) halved

    B) doubled

    C) 1/4 times the original value

    D) unaffected

    Correct Answer: B

    Solution :

    (b) doubled We know that, \[L=\frac{{{\mu }_{0}}{{N}^{2}}A}{l}\] Now, \[N'=2N\] and \[l'=2l\] \[\therefore l'=\frac{{{\mu }_{0}}{{(2N)}^{2}}A}{2l}={{\mu }_{0}}\frac{4{{N}^{2}}A}{2l}\]             \[=\frac{2{{\mu }_{0}}{{N}^{2}}A}{l}=2L\]


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