J & K CET Engineering J and K - CET Engineering Solved Paper-2004

  • question_answer
    A \[1\text{ }m\]long wire is lying at right angles to the magnetic field. A force of 1 kg wt. is acting on it in a magnetic field of \[0.98\text{ }T\]. The current flowing in it will be

    A)  \[100\text{ }A\]        

    B)  \[10\text{ }A\]

    C)  \[1\text{ }A\]           

    D)  zero

    Correct Answer: B

    Solution :

    Force on a current carrying wire of length l, carrying current i, kept in a magnetic field B is given by \[\vec{F}=i\,\vec{l}\times \vec{B}=iBl\,\sin \theta \] where \[\theta \] is the angle the wire makes with the magnetic field. Given, \[l=1m,\,\theta ={{90}^{o}},\,\,F=1kg-wt=9.8N,\] \[B=0.98T\] \[\therefore \] \[i=\frac{{\vec{F}}}{lB}=\frac{9.8}{0.98\times 1}=10A\]


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