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NEET Sample Paper NEET Sample Test Paper-86

  • question_answer
    A coil of circular cross-section having 1000 turns and \[4\,\,c{{m}^{2}}\] face area is placed with its axis parallel to a magnetic field which decreases by \[{{10}^{-2}}\] Wb \[{{m}^{-2}}\] in \[0.01\,\,s.\] The e.m.f. induced in the coil is:

    A) 400 mV

    B)        200 Mv

    C) 4 mV   

    D)        0.4 mV

    Correct Answer: A

    Solution :

    [a] Given: No. of turns N= 1000 Face area, \[A=4c{{m}^{2}}=4\times {{10}^{-4}}{{m}^{2}}\] Change in magnetic field, \[\Delta B={{10}^{-2}}wb{{m}^{-2}}\] Time taken, \[t=0.01\,s={{10}^{-2}}\sec \] Emf induced in the coil \[e=?\] Applying formula, Induced emf, \[e=\frac{-d\phi }{dt}\] \[=N\left( \frac{\Delta B}{\Delta t} \right)A\,\cos \theta \] \[=\frac{1000\times {{10}^{-2}}\times 4\times {{10}^{-4}}}{{{10}^{-2}}}=400\,mV\]


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