JEE Main & Advanced Physics Electro Magnetic Induction Question Bank Static EMI

  • question_answer
    Average energy stored in a pure inductance L when a current i flows through it, is                                            [MP PET/PMT 1988]

    A)            \[L{{i}^{2}}\]                         

    B)            \[2L{{i}^{2}}\]

    C)            \[\frac{L{{i}^{2}}}{4}\]      

    D)            \[\frac{L{{i}^{2}}}{2}\]

    Correct Answer: D

    Solution :

               As we know \[e=-\frac{d\varphi }{dt}=-L\frac{di}{dt}\] Work done against back e.m.f. e in time dt and current i is            \[dW=-eidt=L\frac{di}{dt}idt=Li\ di\] \[\Rightarrow \ W=L\int_{0}^{i}{i\ di}=\frac{1}{2}L{{i}^{2}}\]


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