JEE Main & Advanced Physics Electro Magnetic Induction Question Bank Self Evaluation Test - Electromagnetic Induction

  • question_answer
    A cylindrical region of radius 1 m has instantaneous homogenous magnetic field of 5T and it is increasing at a rate of 2T/s. A regular hexagonal loop ABCDEFA of side 1 m is being drawn in to the region with a constant speed of 1 m/s as shown in the figure. What is the magnitude of emf developed in the loop just after the shown instant when the corner A of the hexagon is coinciding with the centre of the circle?         

    A) \[5/\sqrt{3}V\]

    B) \[2\pi /\sqrt{3}V\]

    C) \[(5\sqrt{3}+2\pi /3)\,V\]

    D) \[(5\sqrt{3}+\pi )\,V\]

    Correct Answer: C

    Solution :

    [c] The induced emf across the ends B and F due to motion of the loop, \[{{e}_{1}}=Bv(BF)=5\times 1\times 2\,\sin \,{{60}^{o}}=5\sqrt{3}\,V\] The induced emf across the loop due to change in magnetic field \[{{e}_{2}}=A\frac{dB}{dt}=\frac{\pi {{R}^{2}}}{3}\left( \frac{dB}{dt} \right)=\frac{\pi {{(1)}^{2}}}{3}\times 2=\frac{2\pi }{3}V\] So, \[e={{e}_{1}}+{{e}_{2}}=\left( 5\sqrt{3}+\frac{2\pi }{3} \right)V\]


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