KVPY Sample Paper KVPY Stream-SX Model Paper-19

  • question_answer
    A sliding wire of length 0.25 m and having a resistance of \[0.5\Omega \] moves along conducting guiding rails AB and CD with a uniform speed of 4 m/s. A magnetic field of 0.5 T exists normal to the plane of ABCD directed into the page. The guides are short -circuited with resistances of 4 and \[2\Omega \]. as shown. The current through the sliding wire is: 
     

    A) \[0.27\,A\]

    B) \[0.37\,A\]

    C) \[1.0\,A\]

    D) \[0.72\,A\]

    Correct Answer: A

    Solution :

    the induced emf across the sliding wire \[e=Bv\ell =0.5\times 4\times 0.25=0.5V\]
    The effective circuit is shown in figure.
    The equivalent resistance of the circuit
    \[r=\frac{4\times 2}{4+2}+0.5=1.83\Omega \] Now, \[i=\frac{V}{R}=\frac{0.5}{1.83}=0.27A\]


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