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NEET Sample Paper NEET Sample Test Paper-52

  • question_answer
    A metallic circular loop of radius r is placed in uniform magnetic field B acting perpendicular to the plane of the loop. A naughty boy pulls diametrically opposite corner so that after sometime the loop changes into an ellipse of major and minor radius a and b. If total resistance  of loop is R and it remains constant during the pulling, the average charge flowing through loop during pulling is-

    A) \[\frac{B(\pi ab)}{R}\]                

    B) \[\frac{B(\pi ab-\pi {{r}^{2}})}{R}\]

    C) \[\frac{B\pi {{r}^{2}}}{R}\]                 

    D) \[\frac{B\pi br}{R}\]

    Correct Answer: B

    Solution :

    \[\Delta Q\,\,=\,\frac{\Delta \phi }{R}\,\,=\,\frac{{{\phi }_{f}}-{{\phi }_{i}}}{R}\,\,=\,\,\frac{B(\pi ab-\pi {{r}^{2}})}{R}\]


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