Electro Magnetic Induction And Alternating Currents Question 485

Question: A superconducting loop of radius R has self-inductance L. A uniform and constant magnetic field B is applied perpendicular to the plane of the loop. Initially current in this loop is zero. The loop is rotated by $ 180{}^\circ $ . The current in the loop after rotation is equal to

Options:

A) zero

B) $ \frac{B\pi R^{2}}{L} $

C) $ \frac{2B\pi R^{2}}{L} $

D) $ \frac{B\pi R^{2}}{2L} $

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Answer:

Correct Answer: C

Solution:

  • Flux can’t change in a superconducting loop.

    $ \Delta \phi =2\pi R^{2}.B $

    Initially current was zero, so self-flux was zero.
    $ \therefore $ Finally $ Li=2\pi R^{2}\times B $ $ i=\frac{2\pi R^{2}\times B}{L} $



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