JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank Self Evaluation Test - Alternating Current

  • question_answer
    Charges on the capacitors in four oscillating LC circuits vary as follows: (1) q=2 cos 4t, (2) q =4 cos t, (3) q = 3 cos 4t, (4) q = 4 cos 2t, with q in coulomb and t in second. In which circuit(s) current amplitude is greatest?

    A) (1)       

    B) (2)   

    C) (3)   

    D) (4)

    Correct Answer: C

    Solution :

    [c] \[{{i}_{1}}=\frac{dq}{dt}=\frac{d}{dt}(2\,\cos \,4t)=-8\,\sin \,4t\], \[{{i}_{2}}=\frac{dq}{dt}=\frac{d}{dt}(4\,\cos \,t)=-4\,\sin \,t\], \[{{i}_{3}}=\frac{dq}{dt}=\frac{d}{dt}(3\,\cos \,4t)=-12\,\sin \,4t\], \[{{i}_{4}}=\frac{dq}{dt}=\frac{d(4\,\cos \,2t)}{dt}=-\,8\,\sin \,2t\] Clearly, amplitude of \[{{i}_{3}}\] is greatest.       


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